Forename and Surnames

As I laid in my bed, wondering if there are more distinct first names or last names? I'm probably not the first person to speculate this question. This could be very useful for many applications in today's world especially with social networking being so incredibly popular. First, I thought there would be more first names because I thought within my own family. Not many difference between last names but most of them had various first names. Then, I thought outside of the family, and thought about how we call some people by their surnames because their forename is so common. This made me curious which name is actual more unique in this world.

What do you think?