Well I can tell you it’s 87% in Holland ;)
I have no statistical evidence either way, nor any scientific proof that women might be good or bad judges. As I have said, my own experience is that they are horrible judges. But I have admitted that it could be a coincidence. The next judge I’m facing is also a woman, let’s see if she’s an exception to the rule so far.
The only thing that might help you however is this: overall, girls have been entering university (and therefore law schools) at an increasing rate over the past few decades. This trend is evident in every single country, and has to do with boys generally studying less at high school (some say too many distractions) as well as the access to education that has been offered to girls in societies that used to be more traditional (even when girls were allowed to study, parents often found it unnecessary and pushed their daughters towards early marriage).
On top of that, women who actually finish law school now have proper careers. My mother (40 years ago) quit law school to help my dad at his own business. Yes, she ended up being a successful businesswoman, but she never became a lawyer (or a judge obviously). Nowadays women follow the paths all the way through, and given that there are an increasing number of graduates in most western countries, it is only a matter of time before almost all judges worldwide are female. I think this might help as background information.
Oh and women should not be judges because periods make them instable (don’t blame me, it’s a US Supreme court ruling :P)