There's huge pressure on parents to get their kids baptized asap. So I think there's a lot of kids in those figures.
JWs are being constantly pressurized to pioneer, too. It's like if you are not pioneering, what's wrong with you?
And let's face it, pioneering is easy compared to years ago. Several people standing around carts playing on their phones. I've seen them in every major city I've visited and it was the same everywhere except Italy, when the JWs were chatting to everyone - but that's lovely Italians for you!
When I pioneered in the 60s I had to do 100 hours a month, we were expected to try and place 100 magazines and do god knows how many return visits (back calls we called them) 75? Plus hold down a job to support ourselves. Hence you'd only get a few pioneers in most congregations and they were usually school leavers still living at home.
So these figures don't surprise me.
I also think people in general are freaked out by world conditions. N.Korea/Trump etc so they want something to cling to that gives them hope.