Cartographers have it easy thanks to the wonderful sets on http://colorbrewer2.org/js/ . The scheme looks inspired by them.
I wonder why this map was done with a divergent scheme though. The data has no midpoint, it makes no sense to diverge like that. And when you zoom out it, due to the diverging lightness ramp it highlights the lightest colors which are 1945 to 1975.
It looks gorgeous but the color choice is not perfect for exploring the data.
You're right to point that out. I agree that a divergent scheme is not the best fit for the data. A simple gradient would have worked best, though it would have been less colourful.
I wonder why this map was done with a divergent scheme though. The data has no midpoint, it makes no sense to diverge like that. And when you zoom out it, due to the diverging lightness ramp it highlights the lightest colors which are 1945 to 1975.
It looks gorgeous but the color choice is not perfect for exploring the data.