I do not think this can be answered in a satisfactory way because there's way too much variation in chickens - breed, age when slaughtered, living conditions, feed, etc. all would affect the proportions, with rather large margins.
That being said, the folks over at seriouseats have an article claiming it's economically viable to buy whole chickens (with guts, even!) and trim and portion them yourself. One thing that definitely makes sense to me is to use a trimmed carcass for really good chicken stock, which can be easily frozen. That alone makes it worth to me to buy a whole chicken: trim the bird, use cuts for whatever, then use carcass for chicken stock. Almost 100% usage, lower cost per weight.
But, on the other hand, if you wanted to make, say, chicken wings for 5-6 people, you wouldn't buy several whole chickens just for their wings. Unless you can effectively store and use frozen temporarily unneeded parts of your whole chickens, I think it makes sense to only occasionally buy whole chickens. That is a) if you cook a lot of chicken and can use up the different cuts shortly after the other or b) if you want and can manage larger masses of frozen chicken that you then use as you need them.