Better still have a student category, and a young adult category of 16-22.
It's about how much leisure income a person has right now, not about what they may earn in future.
A full-time student whatever age is likely to have limited disposable income, but ditto a young person who leaves education as soon as possible and goes to work.
They are likely to be in low-paid employment ans it's also an age when there are likely to be a lot of competing interests for their time and money - gigs, concerts, parties, going out, socialising, girls/boys/both/other, wanting to buy/rent and pay for first car/flat etc...
It's great what we do with the kids but unless we take the holistic approach with regards to young adult and student prices we could lose a lot of these people as they get to 17, 18, 20, 22 - they could drift away - and then suddenly it's 10, 15, 20 years later and "County's something I used to do as a kid" or "I used to go County loads when I was about 14, but I stopped going over the years, don't think I've been for about 8 years now" etc ...