Total unit sales fell 4.5% in 2010, to 717.6 million, at the bookselling outlets tracked by Nielsen BookScan. The decline follows a 3.3% drop in 2009. While some of the decline in print sales was offset by skyrocketing e-book sales, it is unclear if e-book sales jumped enough to totally make up the 34.1 million units that were lost on the print side. Still, the modest decline in print units and boom in e-book sales suggest that the demand for books remains relatively strong despite competition from numerous digital alternatives. And while publishers don't need any more convincing, the BookScan figures show that publishers' future growth is in e-books.

By category, the largest decline came in adult fiction, the segment that appears to be doing the best in the e-book format. The decline in 2010 follows a slight increase in adult fiction in 2009. The smallest decline was in the relatively small juvenile nonfiction segment, where units were down by less than 1%. Juvenile fiction fell 3.5% due in part to the drop-off in sales from the Twilight series. Adult nonfiction remained the largest category, although unit sales fell 1.9%.

The BookScan figures reflect the difficult time the mass market paperback format is having as shelf space at the major retailers diminishes. Units fell 13.3% in 2010, a steep acceleration after units declined 3.7% in 2009. The decline also likely reflects that some of mass market paperbacks' most popular categories, such as romance and mystery, also sell well as e-books. The 9.8% decline in audiobook unit sales is also attributable to the move by consumers toward digital downloads and tightened shelf space.

The hardcover format, which many publishers feared would be hurt the most by e-book sales, fared relatively well in 2010, with units only falling 1.5% after dropping 3.5% in 2009. Trade paperback remained the largest format, selling 380,211,000 units in 2010, a decline of 3.1% from 2009.

BookScan estimates that it tracks about 75% of book sales.

BookScan Unit Sales, 2008–2010

2008*1 2009*2 2010*3 % Change 2009–10
Total*4 777,553,000 751,730,000 717,576,000 -4.5
Adult Nonfiction 301,319,000 282,019,000 276,627,000 -1.9
Adult Fiction 213,034,000 213,989,000 198,587,000 -7.2
Juvenile Nonfiction 37,791,000 37,644,000 37,477,000 -0.4
Juvenile Fiction 160,519,000 159,540,000 154,026,000 3.5
Audio 8,452,000 6,844,000 6,176,000 -9.8
Hardcover 189,107,000 182,345,000 179,681,000 -1.5
Mass Market Paperback 131,207,000 126,306,000 109,520,000 -13.3
Trade Paperback 401,337,000 392,481,000 380,211,000 -3.1

1 For December 31, 2007–December 28, 2008, period.
2 2009 is a 53-week year; in order to keep year-over-year comparisons consistent, week 1 data has been removed from 2009 totals, resulting in 52-week comparison.
3 For January 4, 2010–January 2, 2011, period.
4 "Other" (audio books, maps, calendars, etc.) was excluded from the Category segment; some minor formats have been excluded from Format section.