I find the top three ratios interesting: there's a tiny skew towards females but a huge skew towards males.
It doesn't show what the green threshold is though. From memory, the natural birth ratio is 49:51 m:f, so the female skew is only about 3% while the male skew is about 20%. Seven times larger.
If I were colouring the map, I don't think I'd have bothered with differentiating purple and green, or perhaps used more graduations.