Billboard Year-End Hot 100 singles of 2011
Billboard publishes annual lists of songs based on chart performance over the course of a year based on Nielsen Broadcast Data Systems and SoundScan information. For 2011, the list of the top 100 Billboard Hot 100 Year-End songs was published on December 9, calculated with data from December 4, 2010 to November 26, 2011.
Source: Wikipedia — Billboard Year-End Hot 100 singles of 2011 (CC BY-SA 4.0)