Today in the United States, I think non-smoking is definitely the majority and default (although it wasn't always this way).

Look at public places: often the default is non-smoking and only certain designated areas are smoking. Look at airports. Non-smokers don't go to a little, glassed-in room to sit, while smoking is permitted in the rest of the terminal? Nope, as we all know, it is the exact opposite.

So in the United States I'd think there are FAR, FAR more non-smoking rooms than smoking. While perhaps when non-smoking rooms were first created, only one floor would be non-smoking, today it seems that only two or three floors are smoking!

In Europe and Asia, I have far less experience, but I'd guess that it is just the opposite as the US, because a far, far greater percentage of the population smokes. There is far less accomodation for non-smokers in general in Europe than in the US. For example, a lot of restaurants don't have non-smoking sections, and, unlike the US, they don't have to.