Via David Smerdon, here is the picture:
To oversimplify only a wee bit, it is the countries with less gender equality which have more female chess players, relative to male chess players. Here is some description:
Denmark is the worst country in our list of participation, with only one female player to roughly 50 males, while the rest of Scandinavia as well as most of western Europe also languish at the bottom.
On the other hand, some of the best countries show evidence of the effect of female role models, and would be no surprise to players familiar with women’s chess history. Georgia (ranked 5th) and China (ranked 4th) both featured multiple women’s World Champions. There are also some high rates from a few unexpected sources: Vietnam (1st), the United Arab Emirates (2nd), Indonesia (8th), and even Kenya (12th) really buck the trend. Interestingly, a lot of the best countries for female chess players are in Asia. Besides Vietnam, there are five other countries in the best ten, and if I am a little more lenient with the chess population cut-offs, Mongolia and Tajikistan would also be in there.
Here is one cited hypothesis:
Could it be that, deep down, women just don’t like chess as much as men?
I consider that to be possible, but unconfirmed. In any case, the lesson is that gender imbalance in a particular field can be correlated with greater equality of opportunity overall.