So here's this table that contains
 • Field A, certificates redeemed
 • Field B, certificates issued
 • other fields used as a basis of sorting

I'm ginning up a report, and on each summary line I want to show the total of Field A and Field B, but then I also want to show the Field A total as a percent of the Field B total for that particular subset. I'm sure I've done this in the past, but it appears I'm afflicted with early-onset Alzheimer's or something, because I just can't remember how to do it. But I know somebody on this list does!