I'm not sure what sort of data could support this, but I'll just say this: there is a difference between reading quantity and quality. I'm merely echoing greater critics, but the quantity of books sold says little about their quality (markets see books as commodities and try to make make profit rather than spreading good literature, and this is understandable). Plus, judging by the number of unread books on my shelf, buying a book doesn't mean reading it. There is an aesthetic appeal to books, and though I want to read all I own, there will inevitably be books printed and sold but unread.

There are high literacy rates, but this says little about whether material has been grasped and digested. References to classics (e.g. in the English tradition, Milton, Shakespeare, Dickens) or even religious texts (e.g. Exodus) are rarely recognized, in my experience. Given how freely great orators of the recent past drew from these (e.g. the speeches of MLK Jr.), this is surprising.