E-book sales have increased annually and significantly in all the nine years that the Association of American Publishers have tracked this category. Even so this year's figures are noteworthy.

Sales of e-books in January 2011 had increased 116% over January 2010, jumping from $32.4Million to $69.9M.

The other finding of interest was that while total book sales on all platforms in all categories in showed a slight drop from a year ago, a 1.9% drop from $821.5M to $805.7M those in the  Professional and Scholarly category, i.e. the category including computing and programming titles, grew 1.3% from $51.2M to $51.8M.

Within this category University Press titles were down by around 10%, over 1M so the sales increase in "popular" professional books would have been around 4%.

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