Sales of e-books are booming, although the book market is still a long way from converting completely to digital: last year, print accounted for 85 percent of the publishing industry’s general interest sales, AllThingsD reports.

That number comes from the new BookStats survey, sponsored by two industry groups. It finds that Amazon and other digital distributors are taking an increasing chunk of the market, and that sales of “trade” e-books - basically, everything except educational and professional texts - doubled in the last year.

That helped keep the publishing business more or less flat in 2011, even as print sales dropped off. Net publisher revenue for trade books increased 0.5 percent, to $13.97 billion, with e-books accounting for $2.1 billion of that. Meanwhile overall net revenue dropped 2.5 percent, to $27.2 billion.