The 2016 World Happiness Report reveals that Denmark, closely followed by Switzerland is the happiest country in the world while crisis-torn Syria and Burundi are the most miserable.
The report seeks to quantify happiness as a means of making societies healthier and more efficient. The United Nations published the first such study in 2012.
As with last year, Iceland, Norway, Finland, Canada, Netherlands, New Zealand, Australia and Sweden round out the top 10, making small or medium-sized countries in Western Europe seven of the top 10 happiest countries.
Burundi was the most miserable, followed by war-ravaged Syria, Togo, Afghanistan and six other countries in sub-Saharan Africa -- Benin, Rwanda, Guinea, Liberia, Tanzania and Madagascar as the least happy of 157 countries.
The report compared data from 2005 to 2015 showing that Greece, which suffered enormously from the global recession and now faces a crippling migrant crisis, had the highest drop in happiness.
The United States, where sharp polarization has been exposed in the 2016 presidential election campaign, out-ranked several Western European countries to be 13th most happy nation, up two spots from last year.
Germany was 16th, Britain 23rd and France 32nd. A string of Middle Eastern kingdoms -- Saudi Arabia, Qatar, Kuwait and Bahrain -- out-ranked Italy, which came in at number 50, and Japan, which took the 53rd spot.
China, the world's most populous country, was ranked 83rd and India, the world's largest democracy, came in at 118.
The authors said six factors -- GDP per capita, social support, healthy life expectancy, social freedom, generosity and absence of corruption -- explain almost three-quarters of the variation across different countries.
The report compared levels of happiness in 2005-2007, before the onset of the global recession, with 2013-2015, the most recent three-year period for which data from a Gallup World Poll is available.
Of the 126 countries for which comparable data was available, 55 had significant increases in happiness and 45 had significant decreases, the report found.
Among the top 20 gainers were Thailand and China, eight countries in the Commonwealth of Independent States and Eastern Europe, seven in Latin America, two in sub-Saharan Africa and Macedonia in the Balkans.
The 20 largest losers of happiness included Egypt, Iran, Jordan, Yemen and Saudi Arabia in the Middle East; Japan and India in Asia; and Cyprus, Spain, Italy and Greece in Europe -- all hard hit by the economic crisis.
Ukraine, where the east has been roiled by a pro-Russian insurgency since 2014, has also fallen into the group of 10 largest happiness declines.
Iceland and Ireland offer the best examples of maintaining happiness in the face of economic crisis due to high degrees of social support, the report found.