Book sales have been rising year over year, except around the pandemic. Audio and ebook sales make up a lot of that increase.
> Adult coloring books were the main driving force behind the rise of adult nonfiction 12% sales growth during the first half of 2016 compared to the first half of 2015.
https://wordsrated.com/adult-book-sales-statistics/#:~:text=....
So they have not been “rising year over year.”
(The figures for 2027 are obviously projections and don’t count.)