I was a teen in the '80s, and YA didn't exist really. There were kids' books, all lumped together. But I read Cormier, Duncan, L'Engle, Johnston (my favorite), Stolz, Foley (though this was in my late teens, as I don't believe she started writing until then), Conford (both her mg and tween books), Zindel...those are the ones which come to mind. I didn't read some of the classics (such as Speare or Hunt) until I was in college and took a class on children's lit. Our library, although pretty good, just couldn't have everything -- especially as the kids' shelves were books ranging in targeted age groups from 5-18. I probably stopped pulling from those shelves in junior high and started reading adult books then.
As for no YA in 2003, I suspect that's because you didn't know where to look. As someone who was definitely NOT a teen then (hehe), I was astounded at the wide variety and sheer number of YA books by then. Even in the '90s it began to grow quickly (Tammy Pierce, for example, produced quite a few wonderful books then) -- but I only knew this because I was looking everywhere I possibly could (and also, I had my own income so I could search bookstores).