European statistics:

http://www.europeangodatabase.eu/EGD/Stats_Country.php

1.9% of population in Japan. Although 4.4% of the population desires to play/learn.
7.9% in 10s, 10.8% in 20s, 10.4% in 30s, 6.5% in 40s, 3.2% in 50s, 13.2% in 60s, 48.8% in 70s.

source: in Japanese language
https://activity.jpc-net.jp/detail/srv/ ... tached.pdf
check page four and look for 囲碁

You might find this interesting.
viewtopic.php?f=10&t=14185&hilit=population+report

Around 1/5 of South Koreans play go (I think 1/5th of those are under 18. Mum power.)
Could it be why there are nearly as many strong players from South Korea as China, despite a population 28 times smaller?

_________________
On Go proverbs:
"A fine Gotation is a diamond in the hand of a dan of wit and a pebble in the hand of a kyu" —Joseph Raux misquoted.

It depends what you mean by "play". According to your link, 8 million (16%) of South Koreans know the rules, and 2 million (4%) play casually online or offline, compared to 30 million and 10 million in China, so we can estimate that the Go playing population is 5 times larger in China than in South Korea.