Sales of adult trade books dropped 2.8% in the first half of 2016 compared to the same period in 2015, according to figures released by the Association of American Publishers as part of its StatShot program. Sales in the children’s/young adult segment, meanwhile, rose 0.9% in the same period.

Within the adult books category, sales of downloadable audio had the fastest growth in the period, up 32.6%. The only other format that posted a gain in the first six months of 2016 was trade paperbacks, where sales rose 9.0%.

The largest decline in the six-month span came in the e-book format, where sales fell 18.1%. E-books accounted for 24.2% of adult sales in the first half of 2016, down from 28.7% in the comparable period in 2015. Sales of physical audio dropped 12.7% in the six months, while hardcover sales declined 4.5% and mass market paperback sales fell 2.5%.

The 0.9% sales increase in the children’s/YA category was driven by the paperback and hardcover formats, where sales were up 7.4% and 6.4%, respectively. E-book sales fell 34.9%, and board book sales declined 15.6%.

Looking at the first half performance of the other major categories, the religion category was the only segment that had a sales gain in the period, with sales up 10.4%. Sales of professional books dropped 23.1% in the first six months, while sales of higher education materials fell 5.9% and sales of K-12 materials declined 2.1%.

The StatShot figures are based on reports from 1,210 publishers. For all the reporting companies, sales in the first half of 2016 were down 3.4%.