Statistics can be such a misleading thing -- take the latest: 12% of the United States has eReaders. Not very many is it -- only 12%. Yet, something nags at my mathematical brain -- a stat I remembered hearing. I found a lot of reference to it, but could never verify it, yet it has that ring of truth -- namely, 80% of American households didn't buy a book in the last year (could never find the original source, so it may be apocryphal, but it smacks of relevance when 30% don't know who the US declared independence from in 1776) . Now, that 80% chunk of the population is not going to buy an eReader and even assuming the other 20% buy an equal number of books, eReaders have tipped and most books are now bought in digital format. Amazon's public announcements also mirror this.
Bottom line -- the relevant stat is not what percentage own an eReader, but what percentage of book buyers buy digital books -- and I know that is much higher than 12% . If you want to sell a book these days, you better get it in digital format.