http://blog.wolframalpha.com/2013/01/23/introducing-expanded-personal-analytics-for-facebook/

This is the hourly breakdown of different social apps that we use every day. One┬áthing that will make sure this visualization will not stand the test of scrutiny. There is no mention of the most significant social networking site, Facebook. Another minor but important point to be mentioned here is that I don’t think graduate students will have the same breakdown as someone in their high school.