I am building a report and I am not certain how to display the information quarterly.

The fields are as follows:
Condition1 (checkbox)

I would like to display how many times condition1 occurs per quarter broken down by department and location (see below). As it is currently setup, my report has a dept header and loct header. I can aggregate condition1 in the location header, but I cannot seperate the totals by quarter. Because the locations may change for any quarter, I cannot use DCOUNT to set up the conditions specifically for each location in a given time period. What function can I use to do so?

Dept Location Q1 Total Q2 Total Q3 Total Q4 Total
Unit 1 5 3 5 2
Unit 2 4 7 4 15

Unit 7 10 32 44 13
Unit 10 2 3 5 7

Thank you for your help in advance.