[en] Population Density in Germany

Inspired by http://all-that-is-interesting.com/tag/population/ (the map with the 8 colours), the following map partitions Germany into 16 regions with a population of 5 million each. The 16 largest cities are shown, too.

The "Ruhrgebiet" label stands for 4 of the 16 largest cities. From left to right: Duisburg, Essen, Bochum, Dortmund.
Source for the population figures: German Wikipedia.
Original map: Wikimedia Commons