Hope you're doing well!
I just did a quick sample of this in the attached workbook, and I think that as long as your Measure Values aren't changing, you can just create another Calculated Field averaging all those together. In the attached workbook, that's:
+RANK(SUM([Number of Records]))
You may need to play around if you're doing advanced calculations on the Rank, but hopefully this helps. If you need more help, post a copy of your workbook and I'll be happy to tinker to get the field you're looking for.
Rank.twbx 1.2 MB
Thanks Kathryn! I was running into the difficulty of trying to Aggregate Aggregates, but what you posted worked fine for me.