You tell me which countries have the most escorts there. You can't get a percentage based on nationality there
I've got no idea, it doesn't concern me, do your own research if you want to know.
Your statement, -
"in AW right now. 90% of the girls in AW are Brazilian." - the fact is if you search AW selecting only Brazilians the result is 832, search again and exclude Brazilians the result is 2824 so by simple mathematics you can work out that less than 10% show as Brazilian and circa 90% as other nationalities.
The statement you made is wrong and nothing can change that, Brazilians do not account for 90% of profiles on AW.