Limits to Growth was a 1972 book modeling the consequences of a rapidly growing global population, commissioned by the Club of Rome. Donella Meadows was its leader author.
... the population is spread out with 28.2% under the age of 18, 7.5% from 18 to 24, 33.5% from 25 to 44, 23.9% from 45 to 64, and 6.9% who are 65 years of age or older. ...