In a keynote address delivered at the opening of last week’s Digital Book World conference in New York City, Jonathan Stolper, senior v-p and global managing director for Nielsen Book, presented a series of charts that provided a detailed look at the steadily declining unit sales of e-books. The figures are based on e-book sales reports from more than 30 traditional publishers through the first nine months of 2016, with Nielsen estimating sales for the final quarter of the year.

Based on those estimates, Nielsen found that e-book unit sales from reporting publishers were down 16% in 2016 from 2015. Units fell the most in the juvenile fiction segment, where e-book sales dropped 28% in the year and accounted for 10% of total category unit sales in 2016, down from 14%. (E-books have never been a big factor in juvenile nonfiction and accounted for 1% of units sold in 2016.)

Unit sales of e-books in the adult fiction segment fell 15% in 2016, and, while the format accounted for 49% of all units sold last year in the category, that was down by three percentage points from 2015. E-book unit sales fell 13% in 2016 in adult nonfiction and accounted for 12% of all units sold in the segment last year, compared to 15% in 2015. In total, e-books’ share of trade unit sales was 23% in 2016, down from 27% in 2015.

Stolper offered several reasons for the decline in e-book unit sales, with the most important factor being price. According to Stolper, the return of agency pricing by the Big Five trade houses in 2015 raised e-book prices by an average of $3, leveling off at about $8 per book. That jump in prices coincided with the downturn in e-book sales for traditional publishers. And while e-book prices for the Big Five were rising, prices for self-published books were settling in at about $3. Stolper said Nielsen’s Books and Consumers survey found that price is the top priority for e-book buyers when considering which book to purchase.

A second factor in the decline in e-book sales is the increasing use by book buyers of tablets and smartphones to read e-books and the decline in use of dedicated e-book readers. Consumers who use dedicated e-book readers have consistently been found to purchase more e-books than consumers who use other devices to read. In the first quarter of 2011, more than 70% of e-book buyers said they used dedicated e-book devices to read, a percentage that fell to 24% in the second quarter of 2016.

Whatever the causes for the decrease in e-book sales, the decline has resulted in something that many publishing experts thought would never happen—unit sales of hardcovers overtook unit sales of e-books. With hardcover units up 5% in 2016 over 2015, hardcover’s 188 million units sold topped that of e-books for the first time since Borders closed in 2012, Stolper said.

One of the 40 sessions held during DBW last week focused on “old models made new.” Book of the Month Club’s Maris Kreizman reported that 90% of the people who have subscribed to the BOMC service are women, and 70% of those women are in their 20s and 30s.

In an update on James Patterson’s BookShots program, Trish Daly and Laura Fazio said more than two million copies of the inexpensive, quick reads have been sold. Little, Brown has published 18 titles in the series so far, with 10 hitting a bestseller list.