Suppose we try to organize those countries in the table that Jophiel links to. The lowest ages of first sex are these countries, where it’s between 15.6 and 16.5. I guess we would call them the Nordic countries. We can’t call them the Scandinavian countries, since they don’t speak a Scandinavian language in Finland:
The next group are a group of mostly European countries (in none of which is the main language English), where it’s between 16.7 and 17.8. It includes Brazil and Chile from South American though. Since the list doesn’t include other South American counties, it’s hard to tell what the average is there. It includes Israel, but my impression is that Israel feels culturally more European than Middle Eastern. The list doesn’t include other Middle Eastern countries, so it’s hard to tell what the average is there:
Czech Republic 17.2
The next group are the English-speaking countries of the world, plus four other European countries (France, Switzerland, Greece, and Turkey), where the average is between 17.8 and 18.7.
South Africa 18.7
United Kingdom 18.3
United States 18
New Zealand 17.8
The next group are some more non-English-speaking European countries, plus Indonesia, Taiwan, and Mexico, where the average is between 18.7 and 19.2.
The rest are Asian and African countries (although it’s the only African country the list includes), where the average is between 19.4 and 23:
Hong Kong 20.2
So it’s Nordic countries < a mostly European group of countries with a little lower ages of first sex < a group of English-speaking countries and some other European countries < a mostly European group of countries with a little higher ages of first sex < Asian (and maybe African) countries. I suspect that there’s some way to characterize each group more by culture than by location, but maybe someone else here can do that. Also, let’s note that these are not huge differences. Globalization has pulled the world together in this just as in many things.