Most people who have heard about Bitcoin are those who work in IT, finance and those who read a lot of news (mainstream media are covering Bitcoin sometimes) or have friends who told them. It's really hard to say how much of the population knows about Bitcoin, but I would say it's around 20-30%. Out of those people, only few actually own some BTC, as many think that it's a bubble, or it's just too risky. This means that there's a lot of space for growth, and Bitcoin can be valued at $50,000-100,000 if mainstream adoption will be reached.
Although more and more people have at least heared the term bitcoin already a few times, the percentage of people who are holding some ist still somewhere close to zero.
For example, I have never seen one of those bitcoin accepted stickers in an offline shop.
So the potential for bitcoin is magnificent!