Jim is more or less right. It's a student horn. The date manufactured is more fun trivia than anything. The age isn't going to hurt or help value. And, FWIW, I think they had them before 1998. That's because I bought a YCL-34 in 1991/2 and the "0" in the model name would indicate the first (student) model made. Well, in Yamaha world, at least.
Yamaha has a parts order form on their website -- I have links someplace -- that did have date ranges (no sn ranges) for each instrument. If I remember and can find it, I'll post the link.