5% of the Adult Population can solve "You want to know what percentage of the emails sent by John Smith last month were about sustainability."
https://www.nngroup.com/articles/computer-skill-levels/
Oooh, good one! Already forwarded to a half-dozen of the 5%.
I tried to calculate this myself and got "NAN"
Interesting that Japan is so bad. I'm guessing that's because of the Japanese age distribution rather than the distribution of Zen centers.
I wish I had had this when the design team told me "People will learn it quickly"