I don't think I have ever had one that has the year filled in

Well, that's probably a software thing. The older version of the CDDB didn't even have a field for the year, so software that still uses the old spec won't give you the year even if it is available. For instance, I don't think AudioCatalyst will ever give you a Year field.

If you use newer software that's gracenote-aware, you should get a year filled in a lot more often.