Global ranking / multiplayer matching

I'd like the global ranking system be something connected with personal wealth / earnings. This whole thing reminds me of Railroad Tycoon, where your personal wealth was calculated when the game ended. The global ranking could be based on something like "personal wealth" which is gained by winning games. This is taxed 1% per day. Also your annual earning is a parameter. This is your income for the last 30 days or so.