Snapchat is used by nearly 20% of American iPhone owners

"Still think photo and video-sharing app Snapchat is a novelty sexting app for teenagers? If 5m daily active users and a recent £38.9m funding round hadn't changed your mind, new figures published by analytics firm Onavo might.
The company claims Snapchat was used by 18.6% of all iPhone owners in the US in June 2013, up 10.5% month-on-month, making it the ninth most popular iPhone app there in terms of usage.
Snapchat – which lets people send photos and videos that self-delete after between one and 10 seconds after being viewed – is still a long way behind Facebook (used by 72.5% of US iPhone owners) and Instagram (36.6%), but Twitter's 26.7% market share is within Snapchat's sights."

Source:  The Guardian, 17th July 2013