Twitter is mainly used by older adults who might not have used other social sites before Twitter. Jeremiah Owyang studies social media. He said, "Adults are just catching up to what teens have been doing for years." Only 11% of Twitter's users were 12 to 17 years old in September 2009. This may be because Twitter first gained popularity in businesses and news media that attract more older people. Many famous people such as Shaq, Britney Spears, and Ashton Kutcher are Twitter users.