He is older than HS, he moved around a few times, and probably lost a year because of it. Also, I though this was "college", and he's going to graduate and go to "university" next year.
Is this a Europe thing? In the US we go from HS (four year) to College or University (which is just a bigger College). There are also Jr. Colleges or Community Colleges (different names based on their state), which offer two-year Associate's Degrees, which are lesser than a four-year Bachelor's Degree, generally at much lower per-year costs.