Digital books are now “the dominant single format” in the adult fiction category, according to a new BookStats joint report from the Association of American Publishers and the Book Industry Study Group. eBooks exploded in the adult fiction category last year, accounting for 30 percent of net publisher sales in 2011–up from 13 percent the year before.

At the same time, net sales revenue from eBooks increased from  from $869 million in 2010 to $2.074 billion in 2011. That’s 15 percent of net revenues for publishers. AppNewser has more about how these numbers have affected the total US book market.

Here’s more about those eye-popping figures, from the report: “Adult Fiction eBooks revenue for 2011 was $1.27 billion, growing by 117% from $585 million in 2010.  This translated to 203 million units, up 238% from 85 million in 2010.  Similar to the broader overall Trade sector, the combined print formats also represented the majority of publishers’ revenue in the Adult Fiction category, at $2.84 billion.”

The data was collected from 1,977 publishers, ranging from major publishers to smaller companies. The stats also reflected a dramatic change in the way we buy books. Check it out:

Reflecting broader national trends in consumer purchasing, revenue from sales through online retail grew 35% from 2010 ($3.72 billion) to $5.04 billion in 2011.  This channel, which represented 13% of total publisher net dollars in 2010, grew to 18.5% of the total in 2011 … A notable highlight in BookStats 2012:  direct-to-consumer sales by publishers nearly doubled in revenue and topped $1 billion for the first time.  In 2011, publishers saw $1.11 billion in direct-to-consumer dollars, growing from $702 million in 2010 – an increase of 58%.

Editor’s Note: The original version of this post misstated the number of participating publishers and neglected to mention a partner in the project.