What happens to winrate as you move up levels?

[random50]

40K hands in at 25NL and my win rate is at 3.2PTBB/100 and seems to be slowly edging up. (Pretty pathetic, I know, but for me this is just a hobby to make a little extra pocket money. I'm not bothered about being a great player.)

I am hoping to eventually move up at least as far as 100NL, though. How much of a performance hit is reasonable to expect at each level? In 5K hands at 50NL I'm running at *minus* 2.66. I know this is too small a sample size to be meaningful, I'm just curious to know from other people's experience how likely is a swing in results this dramatic from one level to the next?