Yeah, I realize it'll take some extra time but wouldn't it just be a matter of checking against the current date - 6 months and skipping? Or would it be better just parsing them all out and then making the secondary stats?

As not to kill the server, how about just doing every few days or just set days of the week? (M-W-Sa?)

I think they're might be some interest in a more realistic comparison instead of active participants instead of every entry since the dawn of BOINC.