Here are the sources which I know of, I hope other netters will post other
sources: The original basis for the ten percent figure (which was for
predominately "homosexual"- Kinsey 5 and 6 only) was Alfred Kinsey, et.al.
Sexual Behavior in the Human Male, 1948. A more recent study, reported by
someone else on this net recently, is Robert E. Fay, et.al. "Prevalence and
Patterns of Same-Gender Sexual Contact Among Men." *Science* vol 243, Jan.
20, 1989, pp. 338-348. It is my belief that these figures are highly 
gender, class, and culturally specific, i.e. that they cannot be
generalized outside of the group from which they were taken. The instances
of same gender contact may vary immensely between cultures for example, and
there is evidence that it does. The "meaning" attached to same sex behavior
between  cultures also varies. I suggest for this issue the work of Gilbert
Herdt of the University of Chicago who has written several vols on cross
cultural homosexual/bisexual behavior and the identities, and meanings
attached to such behavior.. The one I have in my library is The Sambia:
Ritual and Gender in New Guinea., 1986.
David E. Woolwine                         717-337-6187   	
Sociology and Anthropology Department     dwoolwin@cc.gettysburg.edu
Gettysburg College
Gettysburg, PA 17325

To the student who wanted "legally verifiable" data on the
percentage of population who are gay. lesbian, and bisexual:
You will find good information in two articles:
Fay, R.E., Turner, C.F., Klasson, A.D., and Gagnon, J.H. (1989)
   Prevalence and Patterns of Same-gender sexual contact among
   men.  SCIENCE, vol 243.

Money, J.  Statement on Antidiscrimination regarding sexual
  orientation.  (1976-77, winter)  Journal of Homosexuality (159)

the thrust of the articles states that lesbigays are underrepresented
in surveys, and that 10% is a reasonable figure.  Good luck, and
maybe some other resources in netland will have more to offer!
(I'd appreciate some better references, too!)
Brian

~