I was confused by the chart. Higher suicide rates cause higher altitudes? If the axes were reversed, the interpretation would seem very different (rate shoots up for a small change in altitude, then levels off at higher altitudes). Also the buckets are unequal (but maybe that's what vingtile means. What is a vingtile, anyone?)
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.
