Hi:
Proc TABULATE will build each column isolated from the other columns. So you cannot, in TABULATE, divide Year3 by Year2 (as an example) or subtract Year2 from Year3 to find a difference (as another example). You can do things like that with PROC REPORT and a COMPUTE block or a COMPUTED report item. Or, you can pre-summarize your data and calc your % differences in a program and then just arrange everything the way you want and do a simple PROC PRINT, but based on the information you've given, TABULATE won't do what you describe.
cynthia