I have a workbook that I update each month for one of our doctors. It contains the $$ amounts for each doctor for the previous month. What he would like to have the workbook do is average across the year tabs ( I have a sheet for 2012, 2013, etc), and give a percentage to compare that doc with the same time last year. I am just getting comfortable using Excel, let alone trying something that seems this complicated. I have no clue as to where to start. Any assistance is greatly appreciated! I've uploaded a dummy sheet to give you an idea what I'm working with.