Is there a way to calculate a ratio based on two sets of dates where the numerator Received Date is independent of the denominator Billing Date (which happens to be in the case key table)? Please see the attached file for the problem example.

For each Billing Date, I am attempting to count the number of Communications received on that same date even though not all Communications received belong to a document Billed on that date. The issue I am encountering is that only those Communications received on the Billing date are included in the numerator of the ratio. The billing document serves as my case key.