From Publishers Weekly:
Sales of adult trade books fell 7.3% in January compared to the first month of 2018, according to the AAP’s StatShot program. Sales in the children’s/young adult category rose 4.3%
The decline in adult sales was due largely to a 19.5% drop in hardcover sales compared to last January, when Fire & Fury was a huge hardcover hit. Mass market paperback also had a weak start to 2019, with sales down 26.6%. Digital audiobook sales showed no signs of slowing in the month, up 37.5% over last January. E-book sales fell 4.1%, according to a composite of data from the 1,374 publishers who report to the AAP.
Link to the rest at Publishers Weekly