Cross Tab Calculation

[amandeepsg]

Hi! All,
Below is what i am trying to acheive in the cross tab.

I am trying to show the conversion over time for trialers.

Let's say there were 1000 trialers in the month of Jan 08 and out of 1000, 100 converted in Jan 08, 200 converted in Feb 08, 100 more converted in Mar 08.  Based on this example this is what i want to show on the crosstab report

                    2008-01         2008-02       2008-03
2008-01           10%               20%             10%



Please help.
Thanks
-Aman