That 13 to 17 year old group is the next generation of social networkers, and they are the 2nd least interested in Facebook.
18 to 25 care about Facebook cause they grew up on it, but the interest falls off as they leave that age bracket.
Your mom and dad are on Facebook. 13 to 17 year olds don’t want to social network with their parents, they’re going to go elsewhere.
Facebook will fall off a cliff in the next five years for multiple reasons, and privacy concerns are just one of them. A major factor is that it’s going to be less and less cool to be on Facebook, and I think it already is, ask some millennials. They’re probably already on to the next thing that is the next Facebook.