Are site owners still republishing articles from article directories?

Yes, it's still working from Ezine Articles, anyway (I think it's pretty unlikely, if your articles are there, that you'll gain much/anything by having them in any other directory additionally).

Bear in mind that it's passive syndication only. It's slow, unreliable and variable. It's only really an afterthought, in article marketing. However, it can be a good and worthwhile and profitable afterthought, and since there's no downside, it can be well worth trying.

The "average" will doubtless be dreadfully low, because the proportion of articles in directories which are of adequate quality for publishers to want to share them with their own already-targeted readers/visitors/subscribers must be absolutely tiny. The majority of people submitting to article directories have very little idea of how article directories actually work and are trying - typically with no success at all - to use them for the "benefit" of their own traffic and/or their own backlinks.

And for another reason, too: the authors whose articles are genuinely written for syndication tend to be the ones who are good at achieving active syndication anyway, by approaching such publishers on their own.

PS (If it needed to be said), make sure you publish them on your own site first, and have them indexed there, before submitting them to any article directory!