What the hell is wrong with the rating here?

Viva Riva! has been rated by 170 users. 130 of the ratings - the vast majority - are between 6 and 10. So how the hell can the average rating only be 6.1? That's ridiculous. IMDb must have fouled up the "weighted average" on this one. Check the reviews - all but two or so rate the movie 9 or 10 stars. The average rating should be much higher.