Tactics Trainer Performance Stats

I've got a couple of questions about the tactics trainer performance page. 

http://www.chess.com/tactics/stats.html

First is under Daily Activity it says something like this,

535/749 Correct (49% accuracy) over 14 Hour

Does anyone know how the accuracy figure is calculated? I would have thought it was just the pass rate but 535/749 = 71%. Is it average score perhaps?

(I think I just answered my question. I think it must be average score.)

Next question. Under themes, what do the percentages mean? Is it pass rate, or maybe average score?

EDIT:

Nevermind, I just moused over the themes graph and got the answer. It's average score.

Thanks, I was about to post the same questions but I got answers here.