E-book sales have better than doubled year-to-year, the Association of American Publishers said. A new study put out on Thursday saw e-book sales surge 115 percent in January to produce $69.9 million in revenue versus just a year ago. The rush came as regular hardcover books lost 11.3 percent of their revenue to hit $49.1 million, paperbacks fell 19.7 percent to $83.6 million, and "mass market" books plunged 30.9 percent to $39 million.
Books on CD or tape were also down slightly, as were textbooks and academic books. Only religious books grew, the AAP said.
Publishers didn't explain the growth but noted that they'd seen significant increases for the past nine years. The new growth gained weight, however, from an already significant e-book market. Amazon alone said that Kindle books started outselling hardcovers on its store last July and began outselling paperbacks this January.
Most of the growth is likely to have come for conventional e-book readers like the Kindle or Barnes & Noble's Nook, which have the majority of share. The iPad, however, has also added a new element by popularizing the concept of reading on a tablet and may have contributed a large amount to the figures. Apple recently reached 100 million total book sales in the first year of the iBookstore.