Teenage money

During a conversation with my Better Half, she suggested that the 50's and 60's had a sea change in entertainment, teenagers had money and entertainers were eager to flatter them.

Which led me to wonder: where did they get their money? From the number of economic illiterates who litter this county I incline to a sneaking suspicion many just got it from their parents' miraculous money well, but apparently the same sort of confusion was popular back in the 20's and 30's.

Some teenage money was earned, but at least since the 70's that's been dropping assuming the years selected are representative: from 1974 to 2014 the proportion of teenagers with a summer job dropped from about 57% to about 33%--a bit over 40% decline. I'd like to know what it looked like from the postwar era on--I'd be interested in seeing if it rose. Since a lot of students didn't finish high school, I'd think it started pretty high--the graph at the link mixes students and the self-supporting.

It may be hard to tease out the information--maybe the details exists for married vs unmarried teenage employment. Before I go diving, does anybody know an easy place to find out?

(I think the decline in summer jobs is terrible. Education isn't just sitting through classes and taking tests.)