I'm not sure how old this data is, but here's a link to The Kinsey Institute's FAQs re: BDSM which sort of answers your question.  If we define BDSM as the "willingness to try bondage or spanking", we're probably talking about a much greater percentage of people.  It's kind of a moving target, in that if something like spanking becomes mainstream, it -- by definition -- can't be considered kinky or deviant anymore.

Hard To Get A Real Count!

When some individuals are scared to admit to the truth!

Thanks for the interesting links - much appreciated

Wouldnt it be good if we could get some serious discussions going on this board ?

The Kinsey institute has a pretty cool website, and a summary about their conclusions around BDSM
are:

http://www.iub.edu/~kinsey/resources/FAQ.html#bdsm

BDSM

-BDSM stands for Bondage, Discipline, Domination/Submission, Sadism/Masochism.
-In a small sample there were no significant differences between BDSM practitioners and the general population on measures of psychopathology, depression, anxiety, OCD, and psychological sadism and masochism. (Connoly 2006)
-A study looking at message board posts found 71% of heterosexual males but only 11% of heterosexual females and 12% of homosexual males prefer a dominant role when engaging in sexual bondage. (Ernulf, 1995.)
-The National Coalition for Sexual Freedom, a national organization committed to supporting the equal rights of consenting adults who practice forms of alternative sexual expression, conducted an  informal survey of SM practitioners in 1998-1999. Some survey results are available on the NCSF website, and indicate that SM practitioners may be at greater risk for harassment, violence, and damage to property.(NCSF, 1999)
-5-10% of the U.S. engages in SM for sexual pleasure on at least an occasional basis (Lowe, 1983).
-12% of females and 22% of males reported erotic response to a SM story (Kinsey, Martin, Gebhard, 1953).
-55% of females and 50% of males reported having responded erotically to being bitten (Kinsey, Martin, Gebhard, 1953).
-14% of men and 11% of women have had some sexual experience with sadomasochism (Janus & Janus, 1993).
-11% of men and 17% of women reported trying bondage (Lowe, 1983).

I think these kinds of statistics are probably low, because few people (especially women) like to talk about or admit openly what they're up to. I also think that the studies are flawed for example the one about message board posts is really only capturing who likes to talk about it online- most women (that I know, besides me ) don't like to run around on the internet detailing their exploits. But it is something.

When I first started thinking about trying to have more kinky experiences, I was a little surprised to find that in the none P4P spanko world, there are far more submissive women than dominants. I'm not sure if this is true for other flavors of bdsm but it certainly seems true for spanking.

In the hobby, the reverse seems true. Perhaps it's more to do with the fact that most women involved in the hobby are doing stuff that's more s+m and less d. Perhaps it's about the fact that you can fake, or at least get into being a dom, but you can't fake being a sub, certainly if you're going to submit to some hard discipline. Thinking about it, it's probably most likely that submission requires a lot of trust, which is difficult in the hobby, for obvious reasons.

I just think it's interesting that the percentages seem to be reversed.