According to Publishers Weekly, title output by traditional methods in 2008 fell 3% to 275,232. However, "the number of on-demand and short run titles soared 132%, to 285,394. The on-demand and short run segment is the method typically used by self-publishers as well as online publishers. With the decline in the number of traditional books released last year and the jump in on-demand, the number of on-demand titles topped those of traditional books for the first time. Taken together, total output rose 38%, to 560,626 titles."
Shelf Awareness reported:
Phenomenal growth in the on-demand books sector was reflected in Bowker's projections that 285,394 on-demand books were produced last year, a 132% increase over 2007's 123,276 titles and 462% above 2006 levels.
Bowker reported that the top five categories for U.S. book production in 2008 were fiction (47,541 new titles), juvenile (29,438), sociology/economics (24,423), religion (16,847) and science (13,555).