Every place I saw was less than 5%. Somewhere between 1/20 and 1/50 is not many. It is a small percentage by anyone's definition.
I do not think society should encourage women to make choices that are bad for their children. You obviously disagree with that.
Small and significant can be the same thing, take a statistics course. Don't use the word if you don't know what it means.
I am fully aware that breastfeeding is the best option, especially for the first six months. We should encourage breast feeding. But, you need to realize that these choices do not happen in a vacuum. The simple fact is that for many families there is no option but to return to work. If we had better family leave in this country, this would be less of an issue. But something tells me you don't support paid maternity leave.