I believe a vingtile is like a quartile, except that there are 20 of them instead of 4 (vingt = 20 in French). So I'm guessing each bucket contains an equal num

I believe a vingtile is like a quartile, except that there are 20 of them instead of 4 (vingt = 20 in French). So I'm guessing each bucket contains an equal number of counties, rather than being an equal size.