Those numbers can't be even close to correct. At worse it's 40% of MRF users that have bothered to even go through the process of the yellow tint test etc....
Whats the % of iMac owners in the world that even visit MRF? I'm guessing it's fairly small.
You really shouldn't be telling people numbers like that in a way that makes it look like 40% of iMac owners with 21.5 inch screens have yellow issues, because it just isn't true.
I agree the figure is likely nearer 80%