It's an interesting question, because I suspect there would be some "Joe Average" consumers who have "security cameras", but might say no to the survey because they equate "surveillance cameras" with something more professional/high-tech/expensive/industrial/commercial.
That's just a guess, of course, but I can think of a few times I've mentioned "surveillance cameras" to people, only to be met with a blank look, until I re-phrase it as "security cameras". MOST people seem to view the two terms interchangeably, but not all.
Anyway, my guess would be around 5%. They seem to be popular items, I know plenty of people who talk about getting a system (usually something from Costco), but not a lot that actually have.