Interesting that this map so closely matches a recent map (US-only) that shows population density with one dot = 1 person. (http://bmander.com/dotmap/index.html)
In the NASA Map, it's probably more like 1 light = 100 people or whatever, but it still seems pretty clear that with few exceptions, population = light.
The exceptions (like the Australian Outback, presumably) are even more interesting, however...
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