After sales growth slowed slightly in April, to 127%, e-book sales rose 162.8% in May, to $29.3 million, at the 13 publishers that report results to AAP’s monthly sales report. Sales for the first five months of the year increased 207.4%, to $148.3 million. In some other trade segments, adult hardcover sales jumped 43.2%, to $138.5 million, at the 17 publishers that report results. Sales at nine mass market paperback publishers fell 14.6% in May, to $53.6 million. For the five months, mass market paperback sales were down 7.3%, to $264.8 million; that decline coupled with the rapid growth of e-books puts the e-book market at 55% of the size of the mass market paperback market.