Formula to restrict selection

[Dov2]

Hi

I have a table like this one:

Column1 Column 2 Column3
xxx Val21 aa
yyy Val22 bb
xxx Val23 aa
xxx Val24 bb


How can I make a report to count how many aa and bb in different column and have also calculated field like

xxx Calculated field Count(aa) Count(bb)
yyy Count(aa) Count(bb)


Is there a formula to say restrict selection for column 3 just for aa, and for column 4 for bb?


Can I use Calculated fields in Cross Tab Reports?
I am using 8.5 Version.

Thanks

Dov2