Hmm, I just found out something that might explain it...

I was told that Poker Tracker reports BB/100 incorrectly, and that my 4bb/100 is actually 8bb/100. I know how much room I have for improvement, so if thats correct, I can believe 20bb/100.

so, is "20bb/100" referring to "20 big bets/100" or "20 big blinds/100"?