Fold to river bet optimal value at 2/4-5/10

[MagicFlea]

mine at 2/4 is 46%, but here are three facts that you can take as you will:

1) My winrate is absurdly high (probably at least 3x what it should be)
2) because I only have 4,500 hands
3) I really suck

on the other hand I've never considered folding too much to river bets to be a weakness. Maybe it's time too look at it?