Actually back in 1998 there were very few submissions, I believe. At that stage volunteers were building the directory mainly by pooling their own bookmarks. When I joined in 1999, I built up categories entirely by listing sites I had found myself. (And to this day submissions are few and far between in my favourite categories, which are all non-commercial.)
As clones of the directory spread (Lycos, AOL, Google) the number of submissions naturally rose. But I suspect that in 1999 the only ones which were not reviewed were those in languages for which we did not have an editor. But we've acquired editors since then for a staggering number of languages. So I doubt if anyone now is going to come across an unreviewed submission from that far back.
But in certain areas of the directory, it's quite possible to find them from two or three years back.