“The good news for publishers, looking forward, is that much of the audience for digital is young. Almost half of those who say they listen to audiobooks were under 35. And it’s a hungry audience. While only 24 percent of Americans say they listened to at least one audio book in 2016, the average listener in that category consumed 15 books in that same period, mostly on a smartphone. You have to figure that the average reader of physical books did not buy 15 books last year, much less read that many.”