The Guardian (citing a May 2012 Nielsen.com [2]) reported that Facebook is #1 (by a wide margin - almost 3x the closest competitor) as measured by the time use

The Guardian (citing a May 2012 Nielsen.com [2]) reported that Facebook is #1 (by a wide margin - almost 3x the closest competitor) as measured by the time users spend on the site. [1] http://www.guardian.co.uk/news/datablog/2012/jun/22/website-visitor-statistics-nielsen-may-2012-google http://www.guardian.co.uk/news/datablog/2012/jun/22/website-... [2] https://docs.google.com/spreadsheet/pub?key=0AuZLaKQQs5xpdGdJNFZEdHhLUXJLa240WmsyZmFWbFE&output=html https://docs.google.com/spreadsheet/pub?key=0AuZLaKQQs5xpdGd...