The third annual World Happiness Report put Switzerland at the top of the list, followed closely by Iceland, Denmark, Norway and Canada. Finland, the Netherlands, Sweden, New Zealand and Australia rounded out the top 10 for 2015.

Germany was placed 26th of the 160 countries studied, not far behind Britain, which placed 21st, and the United States, which did a little better at 15th.

Among the lowest on the list were war-torn Syria and Afghanistan, which were among the bottom 10, along with eight sub-Saharan African countries.

The rankings were based on a number of factors, including real gross domestic product per capita, healthy life expectancy, social support systems and the perceived degree of corruption or lack thereof in government.

Jeffrey Sachs of Columbia University in the United States, which led the study on behalf of the United Nations, told a press conference in New York on Thursday that the top 13 countries were the same as in last year's report, although their order had shifted.

Sachs, who was one of the authors of the report, said the winning formula for all 13 was relative affluence combined with strong social support networks and relatively accountable systems of government.

"Countries below that top group fall short, either in income or in social support or in both," he said.

Sachs said the report would be widely distributed at the United Nations and that he expected that it would be carefully read by governments all over the world.

"We want this to have an impact, to put it straightforwardly, on the deliberations on sustainable development because we think this really matters," he said.

'Networks that connect people'

Another co-author of the report, John Helliwell of the University of British Columbia, told the CBC, Canada's public broadcaster, that although affluence played a major role in happiness, "the importance of social factors and the norms and networks that connect people" was a theme that cut through all levels of income.

This, he said, included "everything from the degree of trust and collaboration in the workplace to time spent with family and friends, for example."

The other co-author, Richard Layard from the London School of Economics, stressed the importance of an individual's childhood to how happy they could be expected to be in their adult lives.

"We must invest early on in the lives of our children so that they grow to become independent, productive and happy adults, contributing both socially and economically," he said.

pfd/bk (AFP, dpa)