[jekylljuice]

It seems to be quite a common technique in animated shows that time supposedly elapses but the characters themselves appear to be frozen in their current age...particularly those in which some of the most prominent characters are children or young people who would be continously changing over that period. The Simpsons is probably one of the best examples - if the characters aged accurately with every passing year, then Bart Simpson would be, what, in his late twenties by now? And how many truck-loads of anti-growth hormones must those danged Rugrats have gotten through in order to remain babies for all that time?

You can look at it as a paradoxial way of both ensuring continuity and completely disparaging it at the same time...did that make any sense at all? No? Well, maybe "constancy" is a more appropriate term than continuity. And personally I like it. So delightfully Beckettian.

At any rate, it's one of those things which you can get away with in animation but basically couldn't in a long-running live action show, wherein you can see the flesh-and-blood cast visibly aging with each season, and the problem would eventually need to be addressed. Make-up and prosthetics can only do so much.