I have a theory.
The internet 'porn' industry is huge--everone I'm sure would agree.
Available online is every kind of kink as well as lots and lots of straight and gay vanilla pornography.
If one were to figure out (and I know this would be impossible) what percentages of each 'flavour' of kink is out there and compare the numbers to the amount of what we could call 'vanilla porn,' could that perhaps give some indication of the percentage of the population that is kink-inclined? I wonder.
The thing is... there will be a percentage of the population who is into D/s... but a number of those are the type of people who will never act on their fantasy, and I believe there will also be a number of those people who don't even know (call it latent kinky inclinations).
BUT... when given free reign to look at what they wish (i.e. the internet in the privacy of their home) we get a truer number, or indication of a number.
For a really obvious example take a really 'out-there' kink...such as bestiality. Say 4.5% of the population is wired to like it... but there is no way that many people will ever even consider acting out... or walking into a shop and buying a movie including it. BUT... give a sample of the population the internet, without consequences... maybe hat same 4.5% or close too it surf sites with that particular kink.
How did I start thinking of all this? Well... walking down the street looking at people everyday and wondering... just HOW not-normal am I?