adding "x" number calculated columns dynamically based on the data columns and adding totals to the end for all the columns

Hi,

I have a cross tab report that shows the salary , and bonus for "x" number of years. Here "x" is a user supplied parameters for example if user selects x = 3 , then the report will show the salary , and supplements for last 3 years for all the employees. if user selects 4 then 4 years of data and so on. The requirement is the display the % change from one year to next after all the years of salary and bonus are rendered. And at the end to show the total for both salary and supplements. Then the % change for the total  is also need to be rendered. I have attached an image with this to help visualize what the requirements are. If the putting the total is difficult , then at least how to add variable number of calculated columns for the % change ( if 2 years selected then 1 % column, if 3 years selected then 2 % column,  if 4 years selected then 3 calculated columns etc. )

Thanks