Rolling 12 calculation for previous years

Hi. I am trying to calculate the R12 YOY % Var for sales, but across multiple years. 

The most recent data I have is for the month of March 2017 so I would like the YOY % Var to be between the periods of March 2016-March 2017 (R12) vs. March 2015-March 2016 (LY_R12)... and also the YOY % Var for R12 for 2 years ago, and so on.  This image below is what I would like the final result to look like. 

Any help is appreciated. Thanks!