It tries to balance color allocation for both players. It is very possible to get a string of blacks in the short term but overall, it will even out to close to 50/50.
In looking at your stats, that appears to be close. Though, if you end up aborting when you get black, you may find yourself getting longer strings of them in that attempt to balance.
Damn, why I always got black pieces when search for games..how does chess.com algorithm work