Subtract colums in pivot table
 

I have a pivot table that has the following characteristics (Excel 2007):
-rows (down the left) are values: "# Employees", "Total Pay"
-Columns (across top) are Dates

I want to calculate the difference between different date columns.

Example:

I have:

Date
5/23/2010 5/16/2010 5/24/2009 Total
# Emp 10 15 5 30
Pay 1000 15000 500 16500

I'd like:

Date
5/23/2010 5/16/2010 5/24/2009 Total Vs. Last Wk % Change Vs. Last Yr % Change
# Emp 10 15 5 30 -5 -33% 5 33%
Pay 1000 5000 250 6250 -4000 -80% 750 15%


Can anyone tell me how to create these columns? The dates will change each
week, but it will always be the difference of col 1 vs col 2 and col 1 vs col
3.

Please let me know if this is unclear or you need more info. Thanks

(PS Not sure how this will display on the board. If there is a trick to
posting excel data into these messages so that it lines up correctly, please
share! Thanks.)