Yeah, this is pretty accurate. I think most NBA games are around 18-25k. Most MLS stadiums seat about 20k although the Seattle Sounders stadium holds about 40k and they actually fill it. High end MLB is in the 40s but low end in the teens so that's a good average.NFL draws the most with about 65-70k, NBA draws a little less cause the arenas are smaller, MLB 25-30k range, then MLS draws about 15-20k
EDIT: Theses are attendance figures not earnings lol.
NCAA (American) Football holds 80-105k for most of the major schools.