From Washington Post:
https://www.washingtonpost.com/news/wonk/wp/2016/03/08/how-much-life-has-changed-in-one-incredible-chart-about-dating/
https://www.washingtonpost.com/news/wonk/wp/2016/03/08/how-much-life-has-changed-in-one-incredible-chart-about-dating/
I am not sure why potential mates meeting in college has declined.