DoubtingBro: As far as current makeup, in my congo there are some kids but honestly maybe out of 110 or so publishers, only about 10-15 unbaptized publishers who are minors. There are just a couple of minor baptized kids.
I have been looking at some data and what you describe would fit the demographic structure of the general population in the States.
There is a bit of variance from country to country but the percentage of publishers who would be of minor age would fall between 10-15% if the JW demographics are similar to the population at large.
When I was a kid, the number of UBPs was much higher and I know we probably had 30 or so out of 100 publishers. I think that JWs aren't having as many kids as they used to (English - USA)
I think that the higher percentage of JW minors in years past is a reflection of population trends in general. The post-war years had more children in ratio to adults - the end of baby boomer years saw a decline in birth rate
When I was young, the ratio was much the same as you say. I found an old photo that was taken in 1971 of the congregation I attended and the percentage of minor publishers in the photo is about 25%.