Bowker, the ProQuest group that supplies book information to publishers, libraries, and booksellers and is the official US agency for identifying ISBN numbers, released the results today of its most recent study on self-published books, both print and digital. According to the release on the study, available self-published books now total more than 235,000, nearly a triple increase over the course of the last six years.

“Self-publishing is now supported by a sophisticated and highly accessible support structure,” said Beat Barblan, Director of Identifier Services for Bowker, an affiliate of information powerhouse ProQuest. “It’s provided everyone who has a story to tell with a method for sharing it and leveled the playing field to an unprecedented degree. This is no longer just vanity presses at work – self-publishing is out of the dark corners and making its way into the mainstream. Notable success stories include a number of self-published authors landing their titles onto the prestigious New York Times bestseller list for ebook fiction.”

Last year, news from Bowker showed that self-published books accounted for nearly 43% of print books. Also, ebooks are increasing in number among self-published titles, as digital publishing platforms become more common and more user friendly.

“Bowker’s research into self-publishing was prompted by an earlier study that showed 2011’s 148,424 self-published print books represented about 43 percent of that year’s total traditional print output and contributed to the first significant expansion in print production since 2007. While print accounts for 63 percent of self-published books, e-books are gaining fast. E-book production in 2011 was 87,201, up 129 percent over 2006. Print grew 33 percent in the same period.”

Amazon’s CreateSpace holds the top position for print production of self-published titles, with 39% of the industry in 2011, while Smashwords produced more self-published ebooks than any other platform with 47% of the market. Penguin’s Author Solutions and Lulu rounded out the top platforms.