implement the count function in webi as per crystal reports count formula

hi,

I have to implement the below formula from a Crystal Report in a webi report.

({@Monthly_amount}/Count ({SP.PROCESS_ID}, {SP.PROCESS_DT}, "monthly"))*100

Please help me on how to implement the same in a webi report.  I am using BO 4.0 infoview client.

Regards,

Priyanka