Posted By:
robert aI'm gonna try to complicate this discussion as much as I can. 
With many E issues, I believe there are quite a few more hofers floating around than commons. I think E93, E98, and E97 (to a certain degree)collectors would agree with this as a couple of the tougher cards in each set are common players. E95 and E96 are pretty completeable overall, but I still see more hof players than commons.
This doesn't have to do with how many were printed or if they were all printed on the same sheet. Common sense tells me that early consumers and collectors were more likely to hang on to Ty Cobb then Hippo Vaughn.
On the other hand, in today's market, collectors are likely to hoard/collect hof players like cobb and wagner. This evens things out a bit. The E90 Jackson is a good example of a card that is not known as being short printed or particularly hard to find, but very collectible which makes the card unavailable to most.
Futher, many E and T collectors that I know only collect Hof types of Cobb, Wagner, Young, Plank, etc. This sometimes makes these cards expensive and tough to find.
Overall, I guess it depends on what player we are talking about in terms of how many exist. Exact numbers aren't possible.
Compared to T206 with common backs, I would say E98, E94 are at least 100x harder to find. At any given time on ebay, it's 700-800 T206 or so to less than 5 E94s.
Scot: You're right about the "sweet spot." E97 commons do not do well for how tough they are because the set is so very hard to complete that a lot of collectors back off.