Final estimates released this morning by the Association of American Publishers show that total industry sales dipped 0.6% in 2015 compared to 2014. They fell to to $27.78 billion, from $27.96 billion in 2014. Unit sales rose 0.5% to 2.45 billion.

The two trade nonfiction categories had the strongest gains in the year, with sales in the children’s/young adult nonfiction segment up 17.0%, to $$617 million. Adult nonfiction sales rose 10.9%, to $5.51 billion.

The increase in children’s/ya nonfiction was not enough to offset a 6.1% decline in sales in the children’s/ya fiction segment and total revenue in the children’s category last year fell 3.3%. Adult fiction sales inched up 1.1% in the year, giving adult trade a 6.0% increase in sales in 2015. The overall gain for trade was due in part to the popularity of adult coloring books.

Another bright spot for the trade market was downloadable audiobooks where sales rose 37.6%, to $551.7 million, and units increased 41.1%. The AAP reported that trade e-book sales fell 11.3% in the year, to $2.84 billion, while units fell 9.7%.

Both the hardcover and trade paperback formats posted sales gains in 2015 with trade hardcover sales up 8.3% and trade paperback rising 2.7%. With trade e-book sales falling and sales in the two major print formats increasing, e-books’ share of trade sales fell to 17.3% from 19.3% in 2014.

Sales in the two educational publishing categories dropped in the year. Revenue in the pre-k-12 education market fell 3.8%, to $4.11 billion, and sales in the higher education category fell 7.6% to $4.49 billion.

The AAP also found that trade sales though physical and online retailers both rose in the year. Sales through physical retail increased 1.8% in 2015, while sales through online retailers rose 3.3%. Online retail accounted for 32.8% of trade revenue last year, a slight gain from the 32.5% share in 2014, while the share pf sales through bricks-and-mortar stores account for 24.9% of sales, up from 25.3% in 2014.

The final AAP figures are derived from a combination of actual sales from over 1,200 companies that report directly to the association, and estimates that reflect sales from publishers which do not report to the AAP. The new figures are relatively close to the numbers the AAP released earlier this year based on sales from reporting publishers. At that time, sales from reporting publishers were down 2.6% compared to the 0.6% decline found in the final figures.