There have been reports from both the USA and the UK on the decline in e-book sales and the ‘resurgence’ of print, but, as usual, the Anglo-American situation of members of the respective publishers’ associations, is not repeated in other parts of the world.
Here’s an interesting example of that from Romania:
http://www.business-review.eu/news/survey-in-2017-1-in-2-readers-chose-audiobooks-and-e-books-152549
If that figure of 50% of book sales being made up of e-books and audio books is correct, it must be one of the highest proportions in the world, if not the highest.
My guess is that there is no decline in ebook sales at all – ebooks are just flying below the radar of clasical publishers and librarians. Here are some usefull data: http://authorearnings.com/
That’s certainly true for a lot of self-published and Amazon-published stuff, I’m sure, Miha. The ‘official’ statistics are never complete, as Author Earnings has shown on more than one occasion.