UPDATE: Additional view showing relative volume, rather than percentage.
For most of our titles, we offer three different (DRM-free) formats: PDF, EPUB, and Kindle-compatible Mobipocket. PDF continues to be the most popular format, though it’s losing ground to EPUB (and to a lesser extent, Mobi). We’ve been tracking which of those three formats customers actually download after purchasing (it’s of course possible that they download multiple formats), and here’s the breakdown over the last 16 months:
And here’s the same data in terms of relative volume, rather than percentages: