Proporitional circle map

A range graded proportional circle map is a map that uses circles to show data that are divided into groups, like countries or states if in the US. The main object of this type is to make the size of the circle to correlate directly to the quantity for that data given in the symbol key. Like this map of the population of Europe.
http://www.d.umn.edu/geog/cartfolder/HTML%20Pages/Map-Types.htm