Fortune's April article [1] on the investment firm Piper Jaffray's 'Taking Stock with Teens' survey [2] shows that in their Spring 2016 survey Snapchat has tied or surpassed Instagram for most important social network among teens; the article includes a graph of the last 3 surveys. Mediakix, which specializes in social influencer marketing, publishes periodic assessments aimed for marketers about the social networks -- with sources. In January they compared Bloomberg and Fortune articles to conclude that Snapchat's video views surpassed those of Facebook [3].

[1] http://fortune.com/2016/04/13/snapchat-instagram-piper-jaffr... [2] http://www.piperjaffray.com/3col.aspx?id=4035 [3] http://mediakix.com/2016/01/snapchat-statistics-2016-markete...