Fivestar multiple axis reviews and views
Fivestar Widget

I believe the Fivestar widget stores values as a percent average rather than as a vote average. In otherwords the Fivestar widget is storing a value between 0-100 rather than 0-5. 

When you have a Fivestar widget collecting 0 to 5 stars, each star is worth 20.  This is why when you have an average of '2 stars', your seeing a value of 40. (2*20=40)

To extend this:


A node with 1, 2 star vote will be stored as 40
A node with 2, 2 star votes will be stored as 40
A node with 1, 2 star vote and 1, 3 star vote will be stored as 50




This can easily be fixed by dividing the displayed output by 20.

From there, I believe your view may already be setup properly.

I'll rework my answer if this isn't relevant here.