Pre Flop Raise Percentage.

[Toms]

I have been struggling with trying to get my preflop raise percentage up. I have 12,000 hands at .50-$1 and my pre-flop raise percent is 5.60. I am winning 2.88bb/100. Is this good, ok or should I push it up. I have over 600 big bets in my br but I want to improve on this area of my game before I move up. Any comments or help would be greatly appreciated.