Yeah, that would be interesting to see. Something tells me the results would be troubling, though. Some state may have a horrible tween genre book with sparkled up vampires.Scribd doesn't have that large a penetration, though. I wonder what the data would look like if Amazon calculated it, since they could include both eBook and physical book purchase data.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.