return object from javascript function

Question

How can I return an object from my function to make it usable outside the function?

Here is what I have so far, but all it does is return an empty object.

var database = firebase.database();
var ref = database.ref('userdata');

var sex;
var male = 0;
var female = 0;
var Geschlecht = {};

ref.on("value", function(data) {
 var user = data.val();
 var keys = Object.keys(user);
 // // // Count sex
 for (var i = 0; i <= (keys.length-1); i++) {
   var k = keys[i];
   sex = user[k].sex;

   if (sex===0) {
     male++;
   } else if (sex===1) {
     female++;
   }
 }

 var Geschlecht = new Object();

 Geschlecht.male = male;
 Geschlecht.female = female;


 return Geschlecht;
}, function (error) {
 console.log("Error: " + error.code);
});

console.log(Geschlecht);