Norway has displaced Denmark as the world's happiest country in a new report that calls on nations to build social trust and equality to improve the wellbeing of their citizens.
The Nordic nations were the most content, according to the World Happiness Report 2017 produced by the Sustainable Development Solutions Network (SDSN), a global initiative started by the United Nations in 2012.
Countries in sub-Saharan Africa, along with Syria and Yemen, were the least happy of the 155 countries ranked in the fifth annual report released at the United Nations.
"Happy countries are the ones that have a healthy balance of prosperity, as conventionally measured, and social capital, meaning a high degree of trust in a society, low inequality and confidence in government," Jeffrey Sachs, the director of the SDSN and a special advisor to the United Nations Secretary-General, said.
The aim of the report was to provide another tool for governments, business and civil society to help their countries find a better way to wellbeing, he said.
Denmark, Iceland, Switzerland, Finland, Netherlands, Canada, New Zealand, Australia and Sweden, in that order, rounded out the top 10 countries.
South Sudan, Liberia, Guinea, Togo, Rwanda, Tanzania, Burundi and the Central African Republic were at the bottom.
Germany was ranked 16th, followed by the United Kingdom at 19th and France at 31st. The United States dropped one spot to 14th.
Mr Sachs said the United States was falling in the ranking due to inequality, distrust and corruption. The economic measures that the administration of President Donald Trump was trying to pursue, he added, would make things worse.
"Tax cuts at the top, throwing people off the healthcare rolls ... I think everything that has been proposed goes in the wrong direction."
The rankings are based on six factors - per capita gross domestic product, healthy life expectancy, freedom, generosity, social support and absence of corruption in government or business.
"The lowest countries are typically marked by low values in all six variables," said the report, which was produced with the support of the Ernesto Illy Foundation.
Mr Sachs said he would like nations to appoint Ministers of Happiness, which had already been done in some countries including United Arab Emirates.
"I want governments to measure this, discuss it, analyse it and understand when they have been off on the wrong direction."