The stats @eroticjesus posted are probably pretty close. Those numbers get you winrates of 4-11bb/100 if you average over each position and I don't think you'll see many players that exceed 11bb/100 at small stakes and above. They make me feel like I need improvement in my MP play though
Hey, well these are average numbers from NL-6max-Crusher. Some guys have 40bb/100 on the BTN and 10bb/100 in UTG with winrate of 8bb/100 overall, for example.
You'll need a lot of samplesize to see your true winrates by position. I think it is a bad focus to look into your positional winrates and try to improve it, except you'd played 50k+ hands per position.
The best thing to do is produce confidence intervals. there's a custom stat in PT4 if you have it or if not a youtube video will show you how to do it yourself