I’d like to see the demographics, estimates of where all those guys are from have been made but I’d like to see how accurate the figures are.
If I were ISIS I would create a list of young Muslim men who are not yet radicalized... maybe salted with a few radicals already known to the west.
Then leak that list as if it were not intended to be leaked. Western agents would then follow and harass those Muslims not yet radicalized and cause them to get radicalized.
Standard Alinsky 101.