Please help with month to month calculation (corrected)

Hi all,
I am working on a report that shows monthly activities for a department.
At this point, i have created a crosstab that shows the activities performed by month where it shows the months on top and colums with different services and the count for each month for each service(similar to the grid below)

..........................01/06 -----02/06 -----03/06
incoming calls.........50.............100.......... 80
outgoing calls.........60..............20............15
surveys.................50..............18............34

what I need to do now is to include percentage increase/decrease compared to the previous month. I would appreaciate if anyone can give me suggestions on how to accomplish it wether in a new crosstab that only compares the increase/decrease or a formula included in the existing crosstab. Thanks in advance for your help

PS. I am using visual studio .net 2005

usa_dreamer2002,

I don´t understand only a thing...

You want to put a column between the others, is it ?

Using your example:

01/06 02/06 03/06
incoming calls 50 100 80
outgoing calls 60 20 15
surveys 50 18 34

01/06 02/06 % 03/06
incoming calls 50 100 100 80
outgoing calls 60 20 -66 -15
surveys 50 18 -64 34