Continuously Variable Proportional Circle Map

http://www.esds.ac.uk/international/support/user_guides/gisoverview.asp

Continuously variable proportional circle map, is much like a proportional circle map but instead of the size of the circle representing a number, the circles are spread across a geographical area. Representing variables in "pies" across the map. These maps are very useful in showing age, or ethnicity across a population, each color on the pie representing the amount of that specific variable.