The World Happiness Report is a measure of happiness published by the United Nations Sustainable Development Solutions Network. These variables currently include: real GDP per capita, social support, healthy life expectancy, freedom to make life choices, generosity, trust and residual.
Here is an infogram presenting the data of top 12 happiest countries of the world. Along with it is an analysis of Happiness index score of India and its neighbouring countries. China is the happiest country among them and Afghanistan the least. India is merely ahead of Afghanistan in the rankings.