Bra Sizes

Have you ever wondered why A,B,C,D,DD,E,F,G and H are the letters used to define bra sizes...?
(A) almost boobs!
(B) barely there.
(C)cant complain!
(D)damn!
(DD)double damn!!
(E)enormous!
(F)fake
(G)get a reduction
(H)help i've fallen over and i cant get up...!!!