Interface... how do I get an average??

See picture.

Now... 8 losers out of 250 is 3.2%... HOW do I get this to calculate inside of the interface? Instead of displaying "8" as the number of losers, I want it to display 3.2%. 

I swear Interface "use" to have the ability to do custom formula's... if not, what a major weakness. 

Any help?

I flat-out can not figure this out.