I think something about this may have been posted in the past, but I think
that if the 5% number comes from people who work in breastfeeding clinics or
something similar, it is guaranteed to be much too high. These are the
places where people with problems go. All the people who have no difficulty
breastfeeding (and there are many, despite the way it feels sometimes) never
go to clinics, so the percentage of people with serious problems (such as
insufficient milk) is obviously going to seem high if you are just
considering the clinic patients.

I've been a La Leche League Leader for 20 years. I couldn't even begin to
count all the mothers I have known and worked with, but it surely must be
several hundred at the very least. We see a broader range in LLL because
many women start coming when they are pregnant. As well, when I started out,
I was pretty much the only breastfeeding resource in my community (although
there are many more now).

In all that time, and all those mothers, I have seen only two who couldn't
produce enough milk for their babies despite doing everything "right." Only
two. I have seen a few more who had breastfeeding mismanaged in the
beginning and who never got a complete milk supply - many of these then went
on to breastfeed subsequent babies, confirming my belief that it was the
mismanagement from the beginning. And yes, there have been some with
complicated medical situations - including breast reductions - who could not
produce a full milk supply. But even throwing those in, the numbers, in my
opinion, are well under one percent and don't even approach five percent.

Just my experience - YMMV.
Teresa