Wouldn't it be better to simply scale people not on the amount of things you do, but on how many upvotes you have received over the last 18 months (discard the last six to prevent a set of newcommers from fundamentally changing the vote distribution), that way you are encouraging good postings (according to the local norms, anyway) over just posting things.

You have to be careful, though. Some people post things that are uniformily well recieved (patio11 comes to mind) whereas I have had posts anywhere from -20 or so to +34.