Extra Column In Matrix

Hello,

I'm trying to make a report with the following layout:

Car Sales 2004 2005 Var %
Total 10 20 50%
Green 7 14 50%
Red 3 6 50%

I'm using a matrix and the data is coming from a cube. One dimension called 'Years' is used to fill the matrix columns and the data corresponding to the car sales is filled by a measure called 'Sales'.
I've built part of the example but I can't add the final column ( the VAR% column).
If I try to add a static column in the end it apears only one year.
The behavior that I would like to have is simillar to the situation when we add the Subtotal column. Although, instead the sum() made by subtotal I would like to calculate the variation percentage between years.
Is there any way to add a final column into a matrix avoiding the problem that I'm having or maybe change the behavior of Subtotal column?

Thanks and best regards.

vjn