New data from Bowker Market Research provides more evidence of the slowdown in the growth of e-book sales in 2013, although the format still managed to capture more market share. For the first half of the year, e-book sales accounted for 14% of consumer spending on books, compared to 13% in the first six months of 2012. E-books’ share of spending rose by four percentage points in 2012, compared to the previous year. The format did increase its share of unit sales by a more significant rate, accounting for 30% in the first six months of 2013, up from 27% of unit sales during the same period in 2012. The difference between the growth of e-books’ share of unit sales and the growth of the format’s share of spending reflects the fact that digital books have lower prices than physical books.

The e-book format was not the only format whose share of consumer spending increased in the first half of 2013. According to Bowker, trade paperbacks also had a one-percentage-point gain, accounting for 34% of spending in the first half of 2013, up from 33% in the same period last year. Paperbacks’ share of unit sales held steady at 28%. The hardcover format saw the biggest declines in the first six months of the year, with its share of spending falling to 34%, from 37% in 2012, and its share of units dropping to 23%, from 26% last year.

Undoubtedly, the slowing of e-book sales growth was a factor in limiting changes to the market shares of the various sales channels in the first half of 2013. In the last few years, the rapid growth of e-book sales helped fuel gains at Amazon and all other online retailers, according to Bowker. While Amazon increased its market-leading share of consumer spending to 29% in the first six months of 2013, compared to 28% in the same period in 2012, all other online retailers saw their share fall by a percentage point. Even as it struggled to compete with Amazon in the e-book space, second-place Barnes & Noble saw its share of book spending rise two percentage points in the period, to 21%, up from 19% in the first half of last year. Walmart was the only other channel (besides online retailers other than Amazon) whose share of spending fell in the first half of 2013. The share of spending attributed to each of the other major sales channels stayed flat in the period.