I read recently that the average bra size in the UK increased from 34B in the 1960's to 36D today. Since I was curious, I wanted to see if there were any differences by country.
There were. Basically, the average breast cup size is coded as follows:
A cup: Green
B cup: Blue
C cup: Yellow
D cup: Orange
More than D cup: Red
Obviously, the is a confluence of several dimensions that determine this, including genetics, age, weight, pendulosity, intentional augmentation, and so forth.