Average age of social network users

Pingdom has published an interesting study regarding the ages of internet social network (i.e. Facebook, Twitter etc.) users in the United States.

The average age is a lot higher than I thought. I would have guessed that most users are teenagers or college kids, but the largest group of users are actually from the 35-44 of age range. And I would never have thought that the average age for Twitter is close to 40 and ‘older’ than Facebook users.