So ignoring how silly "school #10 and #11" is, and Japan's school being called "magicplace"
If the entirety of the UK only has enough wizards for one school of maybe a couple hundred, then it's safe to say Wizards make up a pretty tiny percentage of people.
Either the others-
I know it's old news but whenever people bring up the world outside Hogwarts I just remember that there's 1 school for the British isles...
And the rest of the world looks like this.