Overall, sales of print books are up for 2nd year in a row

With nonfiction, trade paperbacks, leading the way.

Print Book Sales Up Again in 2015.  (Publishers Weekly, 1/1/2016)

Unit sales of print books from outlets that report to Nielsen BookScan increased 2.8% in 2015 over 2014, marking the second consecutive year that print units posted annual gains. In 2014, unit sales increased 2.4% over 2013; in 2015 unit sales were up 5.3% over 2013. Total units sold topped 652 million in 2015 at outlets that report to BookScan, which captures about 80% of print unit sales in the U.S.

Related post:
Book sales:  Print continues to hold its own.  (1/21/2015)