I have just been informed that a sale stat document has been made by One book Shelf (Drivethru RPG and Other sites) to publish sale statistics of Print and play products. They give various information about sales according to product price, type of product, etc.
Unfortunately, board games are only 1% of the sales. Here is the link, enjoy the document:
https://docs.google.com/present/view?id=dczj7vnw_15g3qzhrf5&interval=60&...