You should have reached out to me on this one. I am pretty good at finding accurate old ratings.
It'd be even more accurate to find the hour-by-hour breakdown of these shows to get a more accurate approximation of how many people were actually watching a particular performance.
Oh and are you including American Idol performances? Cuz those have more viewers than anything but the Grammys (and oftentimes even more than that).
This'll be interesting though.