The World Happiness Report 2013 is a study conducted by Columbia University's Earth Institute and published in September 2013 by the Sustainable Development Solutions Network (SDSN). It reveals trends in the data judging just how happy countries really are on a scale running from 0 to 10. The report uses data from people in over 150 countries, surveyed by Gallup over the period 2010-12. Six key variables explain three-quarters of the variation in annual national average scores over time and among countries. These six factors include: real GDP per capita, healthy life expectancy, having someone to count on, perceived freedom to make life choices, freedom from corruption, and generosity. Note: datapoints for 2012 and 2007 refer to national averages in 2010-12 and 2005-07 correspondingly; changes from 2005-07 to 2010-12 are presented for the 130 countries with data in both periods; positive affect in 2005-07 does not include happiness (yesterday) since happiness data were not collected in the period.
Reference: World Happiness Report 2013, Appendix material for Chapter 2 "World Happiness: Trends, Explanations and Distribution", John F. Helliwell & Shun Wang.