This seems to be yet another case where the underlying data is absolutely fascinating, but is let down by the map.

(BTW, I'm reminded of my favourite case of maps being misleading. Look at a red/blue map of the USA, and you come to the conclusion that poor states vote Republican, rich states vote Democrat. However, if you survey individual people, you find that poor people (especially those in rich states) tend to vote Democrat, and rich people (especially those in poor states) tend to vote Republican. And that there are plenty of people whose voting habits run against the geographical and income trends. No particular connection to the maps at hand, just a general reminder that maps can be misleading.)