Is there a website that can tell me the average number of people using an xbox306 game?

I am looking to buy some new games for my xbox360. The type of games i prefer are ones with good online mulitplayer. I want to make sure that there are plenty of people online to make the game worthwhile. Is there a website that can show me what number of people are playing what games on a daily or weekly basis? I do not want recommendations for games here, i just want to know if there is a site i can go see to check for myself.