http://www.zeroscript.net
Lots of graphs, statistics, and forumulas (including productivity).
There are a bunch of formulas, but inparticular to your situation, Zero allows rank by trade prod, ad prod (clicks to ads) or both.
Its my script and has been in development over a year. I have been managing and trading traffic professionally since 2001. Worth checking out because its easy to use and will do what you want.