SEATTLE, WA - NOVEMBER 4: Jeff Ing of Seattle uses a Kindle Fire tablet device at the newly opened Amazon Books store on November 4, 2015 in Seattle, Washington. (Photo by Stephen Brashear/Getty Images)

According to data released by the Association of American Publishers released last week, sales of e-books in the adult trade market declined 16.9% in the first nine months of 2016 over the same period in 2015. E-book sales in this market comprised 22.7% of all book sales in the first three quarters of the year, compared to 26.9% of sales in 2015.

Young adult (YA) and children's e-book sales fared worse, with a 34.2% decline over 2015, where e-book sales made up only 5.6% of sales from the first nine months of the year compared to 8.9% from the same period in 2015. Adult trade sales are routinely separated from YA and children's sales because of the vastly different customer bases.

These conclusions, based on data collected from 1,207 publishers, was predicted with a smaller data set last month: Nielsen Book, which collates data from around thirty publishers, determined that 2016 overall saw a decline of 15% in adult e-book sales, leading to a total decline of 16% in 2016 over 2015, including all age groups.