What percentage of T206 SGC 80/PSA 6 and above and rare backs are slabbed?

[sreader3]

I'd say that 70-80% of T206 cards that would grade PSA 6/SGC 80 or higher are now in slabs. Can I back this up with hard evidence? No. It's based on the fact that the vast majority (> 95%) of the raw cards that I now see on eBay are VG-EX or worse (or trimmed). That wasn't the case 8-10 years ago, when you could at least somewhat regularly find EX or better groups of raw T206s fresh to the hobby.

In terms of rare backs, it depends on what you mean by "rare."