Class and Quorum Attendance Percentage

I had a bishop come to me (Stake Clerk) asking a question I can't seem to answer.

His homepage dashboard shows fairly low percentage for the Attendance > Class and Quorum Attendance chart. For example for the month of March it says 13%.

I went into the full Class and Quorum Attendance report and counted up each line that had a checkmark in the weeks of March for "All Classes" and it came to 101 out of 487 members attended something at least one week. That math comes out to 20.7%. Where is the 13% on the dashboard coming from?

I thought attendance was counting a person if they attended any week during that month, be that in Sunday School weeks or Priesthood/YW/RS weeks.

Any insights as to what "attendance" is based off of and why the numbers above may be out of sync?

A couple of thoughts (gueses): I don't think adult attendance makes any difference as far as budget is concerned. Might it only be looking at primary and youth? (Although numbers-wise, that doesn't seem likely).

If the report is about attendance and not about budget, then it may be counting each class and not just "attended once during the month". I'd think this is more likely.

I had a very similar question asked of me. For the dashboard I was able to match that percentage by adding up all the actual attendees for all weeks and then dividing that by all the potentials for all the weeks. With my question it was why didn't they match the quarterly report numbers. The quarterly report does do how many attended at least once in the quarter. Those are both valid statistics, but demonstrate very different values.