And that number is shrinking as more and more people join Facebook. Back in 2011, a study computed that the 721 million people using Facebook at the time were connected to everyone else on the site by an average of 3.74. "With twice as many people using the site, we've grown more interconnected, thus shortening the distance between any two people in the world," Facebook's research team writes.
If you're logged into Facebook, you can see where you're at on the bell curve of connectivity to the rest of the site's population (I'm at 3.41, just slightly above average). It also shows you how connected CEO Mark Zuckerberg and COO Sheryl Sandberg are (3.17 and 2.92, respectively).
Of course, if you're anything like most Facebook users out there, you've collected a ménagère of random "friends" on the site -- old high school companions you don't really like, co-workers from four jobs ago you haven't talked to since your last day, super-distant family members and the like. Those "connections" might not be all that meaningful, but they're nonetheless contributing to the data that's making us look more connected than ever.