I can't find where is my data of BOINC. As stated in this post written 5 years ago:
The paths for the BOINC directory and BOINC Data directory are stored in the registry, at HKEY_LOCAL_MACHINE\SOFTWARE\Space Sciences Laboratory, U.C. Berkeley\BOINC Setup

So I go to that directory. However, the whole folder only 18.2 MB:

However, when I open the disk usage in BOINC Manager, it says that it has used 553.15 MB:

So where is the rest?