calculate percent of a col in pivot report

Hi,

I have a pivot report based on a query against a database. The query has 3
columns Gender, CntMale, CntFemale

In the pivot report, I need to show the percent of Male, for which I believe
I need to have the column display the value in the CntMale as a percent of
the count of value in column Gender.

I have tried various options in the "Value field settings" but cannot figure
out how.

Appreciate any help !

Thanks,