Hi ~
I am trying to find out the percentage of women who have extended or
protruding nipples versus percentage of those who have inverted, flat
or no nipples. Please advise if this is not enough information for
research.

This characteristic does not exhibit a geographically uniform distribution. 
I seriously doubt that any global statistics-gathering authority has
quantified it. Maybe scientists in the fields of social psychology
(atrractiveness), physical anthropology a.k.a biological
anthropology(biological evolution and  population genetics), and 
evolutionary biology have documented empirical data.

I found an Australian site on breast-feeding that says that about 10%
of women have flat or inverted nipples.

http://www.birth.com.au/class.asp?class=67&page=19

grthumongous-ga ~

Thank you for your thoughts. I'll try searching those suggested areas

myoarin-ga ~

I checked out the link you supplied, Thank you *very* much! That is
the closest to nipple statistics as I have seen to date.

Sorry it took so long to reply, I don't know why but I expected a
email notification to a response to my question.

...still keeping fingers crossed Google Answers can come up with
published stats somewhere.  Thanks again!