Yeah, over here in Thessaloniki we have smoke-free places which I try to support by frequenting. I guess we know the answer to the question "how much of your population needs to do something before it becomes unenforceable?". It's 30%, the percentage of adult smokers in Greece.
To be fair though I'm witnessing a shift the last few years, at least in restaurants/tavernas/fast-food joints. You can more easily find places to eat these days where smoking inside is not allowed.