I seem to remember something about a pint a day - but my kids are teenagers now so a) I've probably forgotten b) even if that was what I was told then, then someone will have decided that it was the wrong amount and they will have changed it!
When my daughter was 2 yrs old (4 yrs ago) it was still a pint a day. I dont think it has changed but like spudqueen says, it probably has. It has probably been changed then changed back again a few times in that time! lol