The really important statistic that is missing here is quite simple:

Far more youth are in university or college.

That is why there are a lot fewer people working but the unemployment rate stayed the same, because people who are school full-time and aren't working or looking for work are neither "employed" or "unemployed".

Other than that yes, those university-age youths who are not attending school full-time have lower paying jobs.  It turns out there aren't as many jobs for people with only a high-school diploma these days, which I don't think is all that big of a surprise to most.