Unit sales of traditionally published e-books fell 10% in 2017, compared to 2016, according to figures released by PubTrack Digital, part of the NPD book group. The service, which tracks sales from about 450 publishers, said e-book unit sales hit 162 million last year, down from 180 million units in 2016.

NPD reported that combining print sales from its BookScan service with PubTrack digital sales, e-books accounted for 19% of total units (both print and digital) last year, down from 21% in 2016. The top selling e-book among the trade publishers, it reported, was The Handmaid's Tale published by Houghton Mifflin Harcourt.

Adult fiction remained the most popular e-book category–44% of sales in the category were in the digital format–but e-book sales in the segment dropped 14% from 2016, to 108 million units.

E-books have a much smaller share of the adult nonfiction market, 12%, but sales in the segment rose 3% last year, to 38 million units, NPD reported.

The steepest decline in e-book sales last year was in the children's category, where sales fell 22%. In children's, the digital format accounted for only 5% of all sales last year. E-book sales were down 8% in the young adult category, falling to 4 million units sold. The format comprised 18% of all young adult unit sales last year.

All the major trade houses, including the Big Five, report sales to PubTrack. The service, however, does not track e-book sales from Amazon's independent authors. In his letter to shareholders earlier this month , Amazon CEO Jeff Bezos said that more than 1,000 authors using Amazon's KDP platform had royalties of over $100,000. A company spokesperson said e-book sales at the company have continued to grow globally through traditional outlets and subscription services, specifically Kindle Unlimited.

Top-Selling Traditionally Published E-books, 2017

Rank Title Author Publisher
1 The Handmaid’s Tale Margaret Atwood Houghton Mifflin Harcourt
2 Origin Dan Brown Random House
3 Camino Island John Grisham Random House
4 Hillbilly Elegy J.D. Vance HarperCollins
5 The Fix David Baldacci Hachette
6 Before We Were Yours Lisa Wingate Random House
7 A Gentleman in Moscow Amor Towles Penguin Group
8 The Rooster Bar John Grisham Random House
9 Big Little Lies Liane Moriarty Penguin Group
10 Two Kinds of Truth Michael Connelly Hachette
11 1984 George Orwell Houghton Mifflin Harcourt
12 The Shack William P. Young Hachette
13 The Late Show Michael Connelly Hachette
14 A Man Called Ove Fredrik Backman Simon & Schuster
15 End Game David Baldacci Hachette
16 16th Seduction James Patterson Hachette
17 A Column of Fire Ken Follett Penguin
18 Come Sundown Nora Roberts Macmillan
19 Small Great Things Jodi Picoult Random House
20 The Subtle Art of Not Giving a F*ck Mark Manson HarperCollins