Proportional Circle Map

http://www.geog.ucsb.edu/~jeff/gis/proportional_symbols.html

Proportional Circle maps are maps that represent data with the use of different sized circles. The map above  is interent users in Europe in 2004. I believe one can conclude that there are a larger number of people who use the interest in Germany. The larger the circle the larger number of whatever is being measured, in this case interent users.