I found one I was thinking of, but it doesn't say wake to feed, it's just wake and need mum or dad's help to go back to sleep. 75% at 6 months, 50% at 12 months and a third at age four. (Gethin, Anni & Macgregor, Beth Helping your baby to sleep)
I think there was another one quoted in an Essence mag article about night feeds....

Outside of a few people I've come across who have left their babies to cry regardless, I can only think of one person who's baby has slept through without night feeds within 3 months (and it didn't last forever).