A new report from Bowker counts more than 235,000 print and digital self-published titles being released annually in the United States.

You can keep track of this marketplace every week through our Self-Published Bestsellers List. Compared to 2006 figures, this year marked a 287 percent increase for the booming section of the publishing industry. At the same time, the marketplace is dominated by four companies: CreateSpace, Smashwords, Author Solutions and Lulu.

Here’s more from the report: “In 2011, CreateSpace dominated the print segment, supporting the creation of 58,412 titles (39 percent of self-published print books). Smashwords topped the e-book producers with 40,608 titles (nearly 47 percent of total self-published e-books). The combined divisions of Author Solutions (part of Penguin Group) produced a total of 47,094 titles and Lulu Enterprises checks in with 38,005 titles. The Bowker analysis shows that beyond these four players, no company has more than 10 percent of market share.”

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