There is already a question about the number of research mathematicians here, but I was wondering :

is it possible to estimate the number of graduate students in mathematics worldwide in 2019 ? (Note that, especially since not all of GS stay in academia, it is quite different from the other question.)

Ideally, what I'm looking for is a graph since 1950, with a break-up by country.

For the US, such a graph can be found on a fine page by the AMS up to 2015-16 data (published in march 2018), although crucially it doesn't mention the yearly number of drop-outs.

So the main aim of my question is to find the equivalent for other countries.