According to Association of American Publishers (AAP) sales figures, adult mass market paperback sales plunged nearly 31 percent in January compared to the same period last year. At the same time, adult hardcover sales fell 11 percent.

Total book sales dipped 1.9 percent over the same period, totaling $805.7 million. eBook sales continued to grow dramatically–eBookNewser has those details.

We’ve embedded the complete release below. Here’s more from the report: ” In the Children’s/Young Adult category, Hardcover sales were $31.2M in January 2011 vs $31.8M in January 2010 (-1.9%) while Paperbacks were $25.4M, down 17.7% from $30.9M in January 2010.”

AAP Reports January 2011 Book Sales