This number is quite large. What limit do you play? This is Hold'em?
You definitely should separate out your shorthanded results. (If you have Pokertracker this is easy to do. Just uncheck the 6-max tables under the preferences tab.) The combination of very loose and very aggressive play by either you or your opponents could account for this. How often do you see a showdown?
Have a look at these threads:
Small Stakes SD
Micro SD
Shorthanded SD