From a Blog Post by Laura Dawson:
A new analysis of U.S. ISBN data by ProQuest affiliate Bowker reveals that the number of self-published titles in 2012 jumped to more than 391,000, up 59 percent over 2011 and 422 percent over 2007. Ebooks continue to gain on print, comprising 40 percent of the ISBNs that were self-published in 2012, up from just 11 percent in 2007.
“The most successful self-publishers don’t view themselves as writers only, but as business owners,” said Beat Barblan, Bowker Director of Identifier Services. “They invest in their businesses, hiring experts to fill skill gaps and that’s building a thriving new service infrastructure in publishing.”
The analysis shows the growing prominence of a handful of companies that offer publishing services to individual authors. More than 80 percent of self-published titles came to market with support from just eight companies, including Smashwords and CreateSpace.
Direct to Full Text Report (6 pages; PDF)
The report contains data about “ISBN Output For USA Self-Publishers, 2007-2012 (Total Print and Ebooks)”
See Also: Bowker Reports that Self-Publishing Continues to Experience “Strong Growth” In U.S. (October 2013)
2012 year-end data.