Year to date data missing in some months

[muraliparamu]

I am trying to create an Year to date report(Crosstab).
There may not be data for all months, in that case the data is missing in the report.
How can I show the previouse month data to those months?

Below is the sample what my report producing now
(Note: Category B in Nov-09 is empty and Category G in Sep, Oct,Dec,Jan also empty)

Category   Sep-09   Oct-09   Nov-09   Dec-09   Jan-10
A           125   140   151   176   220
B   11   14      21   23
C   145   173   193   223   258
D   1,540   1,804   2,055   2,376   2,759
E   23   27   29   32   36
F   170   210   246   269   295
G         4      

And what I am looking for.

Category   Sep-09   Oct-09   Nov-09   Dec-09   Jan-10
A   125   140   151   176   220
B   11   14   14   21   23
C   145   173   193   223   258
D   1,540   1,804   2,055   2,376   2,759
E   23   27   29   32   36
F   170   210   246   269   295
G         4   4   4

[laks]

I think you can achieve this by creating a running total and subtracting actual from running total.

[muraliparamu]

thanks laks for your time.
but your idea not working here.  :(

[laks]

Oops my bad, running_total - actual wont work..