Prove what? When they launched? Yes, I spent about 2 minutes on Google to verify that the first Iphone was released in 2007 and that Facebook and Twitter were launched in 2006 (Facebook was actually sooner but that is when it became available to everyone.)
As far as Social Media and mental health, that is also all over but one example:
Young adults born after 1995 are experiencing more mental health issues. Researchers point to lack of sleep and the rise of social media.
www.google.com
That points to 2010 being an inflection point. If you view the graph posted earlier things held pretty steady through about 2007 (eyeballing as there are 5 year gaps), there is a slight increase, and then an explosion after 2010. So one could just as easily correlate social media and the rise of constant connectedness to the increase in violence.