Show a variance (amount or %) from 1 year to another

[tbone56]

I have a date field covering 2 years of data (sales $ is the value). In the pivot table I have grouped the date into years. So I have 2 columns ie 2012 and 2013. How can I show (in a 3rd column) a variance of the 2 years (either as an amount or a %age). ?
Cheers TBone 56

 

[ChiChiR]

Am I oversimplifying to say you can just do a formula in your third column =2013value/2012value-1 . This would give you the percentage change. I have to be missing something here?