What ducks lay the most eggs (by weight)?

So, I've recently realized that some people raise ducks specifically for the eggs. I always thought duck eggs were more of an occasional delicacy than something you could live off of. So, I ask, what breeds of ducks produce the most eggs (by weight of the total egg production)?

Anyway, I was reading a story about someone in need (I think in Africa) who received ducks from a charitable organization, and she (as well as someone I asked) spoke of the eggs as if they were as frequent as chicken eggs.

Yeah, I've never been a duck farmer, but I've been around ducks, and seldom seen their eggs. So, I thought this was pretty cool news.

[HASH]eggs