According to https://en.wikipedia.org/wiki/List_of_countries_by_medal_count_at_International_Mathematical_Olympiad https://en.wikipedia.org/wiki/List_of_countri

According to https://en.wikipedia.org/wiki/List_of_countries_by_medal_count_at_International_Mathematical_Olympiad https://en.wikipedia.org/wiki/List_of_countries_by_medal_cou..., there are smaller countries performing better (Hungary, Bulgaria, for instance) and similarly as well.