2019 to 2020: 33%

https://www.cnbc.com/2021/03/13/dungeons-dragons-had-its-biggest-year-despite-the-coronavirus.html

2018 to 2019: 65% in Europe (?)

https://www.dicebreaker.com/series/dungeons-and-dragons/news/dungeons-and-dragons-2019-biggest-year

2017 - 2018: 52%

https://www.bloomberg.com/news/features/2019-07-08/how-to-be-a-professional-dungeons-dragons-master-hosting-games

2016 - 2017: 44%

https://www.seattletimes.com/life/lifestyle/behind-the-scenes-of-the-making-of-dungeons-dragons/

Canadian book sales of D&D

Source: https://www.booknetcanada.ca/blog/2018/6/13/the-rise-of-dungeons-dragons