Data Maps give you a quick visual glimpse at city ratings on the World Map. To access this system, click the “Maps” button at the top of the World Map screen.
On the left are several buttons. These are the data maps. Upon selecting a map, its key will appear on the right side. The key will detail what each city's color means. The cities or territories on the map will change color based its data to the corresponding key color.
See the World Map GUI page for more information and pictures on how to access these systems.