That ^ is the largest poll/study I've seen done on this topic. As you can see, the spread is fairly even, with about half of the people getting a score equal to or within a point of their average practice AAMC test score and about 30 percent below and 25 percent above.
And to "How many of you who took the test in 2009 scored above your AAMC practice averages? ".
Well, this poll was started in the fall of 2008. So I would guess that about half of the 191 people who responded took their test in 2009.