I'm sorry for not sharing the data correctly. I'm new using stackoverflow. Here's a try. As Nicolás suggested, I coded:
dput(filter(porc_sc_melt_real, year <= 1920))
and my console printed the following:
structure(list(ccode = c("ARG", "ARG", "ARG", "ARG", "ARG", "ARG", 
"ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", 
"ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "BOL", "BOL", "BOL", 
"BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", 
"BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", 
"BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", 
"BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", 
"BRA", "BRA", "BRA", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", 
"CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", 
"CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CRI", "CRI", "CRI", 
"CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", 
"CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", 
"DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", 
"DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", 
"DOM", "DOM", "DOM", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", 
"ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", 
"ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "HND", "HND", "HND", 
"HND", "HND", "HND", "HND", "HND", "HND", "HND", "HND", "HND", 
"HND", "HND", "HND", "HND", "HND", "HND", "HND", "HND", "MEX", 
"MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", 
"MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "NIC", 
"NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", 
"NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", 
"NIC", "NIC", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", 
"PAN", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", 
"PAN", "PER", "PER", "PER", "PER", "PER", "PER", "PER", "PER", 
"PER", "PER", "PER", "PER", "PER", "PER", "PER", "PER", "PER", 
"PER", "PER", "PER", "PER", "PRY", "PRY", "PRY", "PRY", "PRY", 
"PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", 
"PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "URY", "URY", 
"URY", "URY", "URY", "URY", "URY", "URY", "URY", "URY", "URY", 
"URY", "URY", "URY", "USA", "USA", "USA", "USA", "USA", "USA", 
"USA", "USA", "USA", "USA", "USA", "USA", "USA", "USA", "USA", 
"USA", "USA", "USA", "USA", "USA", "USA", "ARG", "ARG", "ARG", 
"ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", 
"ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", "ARG", 
"BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", 
"BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", "BOL", 
"BOL", "BOL", "BOL", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", 
"BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "BRA", 
"BRA", "BRA", "BRA", "BRA", "BRA", "BRA", "CHL", "CHL", "CHL", 
"CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", 
"CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", "CHL", 
"CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", 
"CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", "CRI", 
"CRI", "CRI", "CRI", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", 
"DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "DOM", 
"DOM", "DOM", "DOM", "DOM", "DOM", "DOM", "ECU", "ECU", "ECU", 
"ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", 
"ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", "ECU", 
"HND", "HND", "HND", "HND", "HND", "HND", "HND", "HND", "HND", 
"HND", "HND", "HND", "HND", "HND", "HND", "HND", "HND", "HND", 
"HND", "HND", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", 
"MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", "MEX", 
"MEX", "MEX", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", 
"NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", "NIC", 
"NIC", "NIC", "NIC", "NIC", "NIC", "PAN", "PAN", "PAN", "PAN", 
"PAN", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", "PAN", 
"PAN", "PAN", "PAN", "PAN", "PER", "PER", "PER", "PER", "PER", 
"PER", "PER", "PER", "PER", "PER", "PER", "PER", "PER", "PER", 
"PER", "PER", "PER", "PER", "PER", "PER", "PER", "PRY", "PRY", 
"PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", 
"PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", "PRY", 
"PRY", "URY", "URY", "URY", "URY", "URY", "URY", "URY", "URY", 
"URY", "URY", "URY", "URY", "URY", "URY", "USA", "USA", "USA", 
"USA", "USA", "USA", "USA", "USA", "USA", "USA", "USA", "USA", 
"USA", "USA", "USA", "USA", "USA", "USA", "USA", "USA", "USA"
), year = c(1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 
1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 
1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 
1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 
1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 
1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 
1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 
1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 
1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 
1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 
1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 
1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 
1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 
1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 
1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 
1916, 1917, 1918, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 
1907, 1908, 1909, 1910, 1911, 1912, 1913, 1917, 1918, 1919, 1920, 
1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 
1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1903, 
1904, 1905, 1906, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 
1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 
1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 
1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 
1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 
1918, 1919, 1920, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 
1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 
1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 
1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 
1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 
1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 
1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 
1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 
1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 
1919, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 
1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 
1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 
1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 
1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 
1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 
1901, 1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 
1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 
1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 
1913, 1914, 1915, 1916, 1917, 1918, 1920, 1900, 1901, 1902, 1903, 
1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1917, 
1918, 1919, 1920, 1900, 1901, 1902, 1903, 1904, 1905, 1906, 1907, 
1908, 1909, 1910, 1911, 1912, 1913, 1914, 1915, 1916, 1917, 1918, 
1919, 1920, 1903, 1904, 1905, 1906, 1908, 1909, 1910, 1911, 1912, 
1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 
1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 
1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 1902, 1903, 
1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 1913, 1914, 
1915, 1916, 1917, 1918, 1919, 1920, 1907, 1908, 1909, 1910, 1911, 
1912, 1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920, 1900, 1901, 
1902, 1903, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1911, 1912, 
1913, 1914, 1915, 1916, 1917, 1918, 1919, 1920), variable = structure(c(3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 4L, 4L, 4L, 4L, 4L), .Label = c("porc_hom_const", "porc_muj_const", 
"porc_hom_real", "porc_muj_real"), class = "factor"), value = c(80, 
83.33, 80, 80, 100, 100, 100, 100, 100, 100, 71.43, 100, 100, 
100, 80, 80, 100, 100, 100, 100, 100, 100, 100, 100, 80, 100, 
100, 100, 100, 100, 55.56, 100, 100, 100, 100, 100, 100, 100, 
100, 100, 58.33, 100, 100, 93.75, 93.75, 93.75, 100, 88.24, 88.24, 
93.75, 93.75, 93.75, 88.24, 93.75, 83.33, 93.75, 93.33, 100, 
93.75, 88.24, 100, 88.24, 100, 100, 87.5, 100, 76.92, 90, 100, 
90, 100, 90.91, 100, 100, 90.91, 76.92, 83.33, 90.91, 83.33, 
90.91, 76.92, 92.86, 100, 76.47, 100, 100, 71.43, 90.91, 78.57, 
100, 100, 69.23, 78.57, 100, 91.67, 84.62, 84.62, 100, 100, 78.57, 
73.33, 68.75, 100, 100, 47.83, 100, 100, 100, 38.46, 38.46, 71.43, 
100, 80, 70, 100, 100, 100, 53.85, 87.5, 85.71, 87.5, 75, 100, 
100, 100, 87.5, 100, 83.33, 83.33, 83.33, 71.43, 100, 62.5, 55.56, 
83.33, 100, 80, 100, 83.33, 62.5, 83.33, 100, 100, 80, 71.43, 
100, 83.33, 100, 100, 100, 62.5, 60, 100, 100, 50, 71.43, 83.33, 
83.33, 83.33, 100, 55.56, 83.33, 100, 100, 100, 100, 100, 87.5, 
85.71, 80, 100, 87.5, 100, 93.75, 75, 92.86, 100, 86.67, 92.31, 
75, 100, 100, 100, 58.82, 100, 75, 100, 100, 75, 100, 100, 100, 
100, 71.43, 100, 83.33, 55.56, 42.86, 100, 100, 80, 80, 100, 
100, 83.33, 100, 80, 100, 100, 100, 100, 100, 100, 40, 100, 40, 
100, 20, 100, 100, 100, 40, 100, 81.82, 100, 90.91, 63.64, 100, 
100, 100, 90.91, 100, 84.62, 90.91, 91.67, 84.62, 100, 91.67, 
83.33, 100, 100, 100, 90.91, 100, 100, 75, 60, 100, 100, 20, 
100, 75, 75, 100, 50, 33.33, 100, 60, 75, 100, 60, 100, 100, 
75, 60, 100, 71.43, 100, 80, 100, 100, 100, 83.33, 100, 100, 
100, 100, 100, 100, 100, 100, 90, 90, 100, 100, 90, 100, 100, 
88.89, 70, 88.89, 100, 100, 90, 100, 81.82, 100, 100, 100, 100, 
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0, 0, 0)), row.names = c(NA, -600L), class = "data.frame")
Does this serve?
Sorry for the inconvenience, and thanks a lot for your help and time!