In the first eleven months of 2017 (the most recently released data by the American Association of Publishers), e-book revenues dropped 5.5% over the same period in 2016, while hardback revenues increased by 3.3% . It's worth noting that paperback and mass market revenues decreased, as well, by 1.7%. The AAP only reports data collected from about 1,200 publishers, so this doesn't tell the whole story. NPD's PubTrack Digital, which reports data collected from about 450 publishers (including the major publishing houses), said e-book unit sales declined in 2017 by about 10% over the year before. Such data paints a fairly bleak picture for the e-book market as we await initial 2018 data.

Source: Forbes April 28, 2018 23:15 UTC