Math Genealogy, https://www.genealogy.math.ndsu.nodak.edu/search.php is a funny site which aims at listing all PhD's in mathematics, with years, place, titles and advisers. Of course it cannot be complete in any sense. But here is a strange thing that I discovered: numbers of PhD by country in each century (the countries are assigned there according to the modern political map).
17 century: Germany 250, Netherlands 85, Switerland 23, Italy 16, England 15, France 13.
18 century: Germany 317, Netherlands 122, England 24, France 14, Switzerland 8, Italy 7, Austria 7.
19 century: Germany 1563, Netherlands 214, USA 214, France 71, Austria 66, Switzerland 54, England 37, Italy 35.
What conclusions can one make from this statistics? That most of mathematics (by far!) in 17-19 century was done in Germany? That Germans (and Dutch) are more likely to report the data then French or British? That Germans and Dutch are better in keeping historical records? Or what?