Same data graphed by Percentage lets you see the trends a little better:
You can see how the population center moves to the right as experience increases
A little bit about the data set and this method. I have a database which has all the OPRs for all the team at each event they play, spanning many years. I take all of the OPRs and group them into catagories, this year it is in segments of 5 points per segement. I have used the "20 slices" method since 2006 to allow me to overlay data from several years worth of competition onto the same chart for analysis of multi year trends even though the games often have very different scoring systems.
Included in the 2011 data set:
Teams who played at least one event = 2053
Teams who played at least two events = 800
Teams who played at least 3 events = 244
Teams who played at least 4 events = 45
Beyond this, the popluations are too small to be relevant.
You can see from the chart some of the things IKE mentions: At 4 events, the teams are clearly limiting one anothers' total performance as indicated by the big peak at 40-45. With multiple robots of this caliber, the per team score actually goes down.