I only buy one or two hardbacks a year (crafts or art books), and dozens, if not hundreds of ebook novels). I often read 2 to 3 novels a week. All are ebooks, as I find it much more comfortable to read a slightly larger font size, and not have to carry around multiple books, in case I finish one.
I'd be interested to know how they selected people to answer the survey. Depending on how they selected them, it could be completely skewed data.