the result of caprice
It may be that this is not precisely defined. I had one of the earliest (I think) editions with the plastic pieces, and there were different numbers of each color even when I first got the game.
I agree with the two above - I originally played with the wood pieces from the early 70's. The count wasn't the same for each color - but we never ran out of pieces either so it didn't really matter (the 'taking over the cubes of a defeated player' rule pretty much made up for the actual cube count).
So you think that the original wood cube and torpedo version and subsequent plastic versions had different counts for each color? Interesting.