Ok, here's what I used. I didn't use your "pre-aggregation" recommendation because I still don't really understand that part, and because the performance from doing just this alone made such...

I spent some more time with your tutorial and finally figured out a solution. Thanks very much for your help. Much more readable and much better performance.

I appreciate the help, but I don't understand how to implement that example. I guess I'll just live with a slow query.