Bangladesh has slipped down five notches in this year's World Happiness Report rankings, but it remains a happier place than India and Sri Lanka.
The issue of migration was placed at the heart of the 2018 report, which also ranked 117 countries according to happiness of their immigrants.
The report, an annual publication from the UN Sustainable Development Solutions Network, said all the Nordic countries scored highly on income, healthy life expectancy, social support, freedom, trust and generosity.
Perhaps the most striking finding of the whole report is that a ranking of countries according to the happiness of their immigrant populations is nearly exactly the same as for the rest of the population.
We cover the report every year, because, happiness. also because the report is intended as a tool to help create positive public policy, including policy directed at helping the planet.
But it wasn't just the Scandinavian countries that made the list - here are the rest of the top ten happiest countries in the world.
"The most striking finding of the report is the remarkable consistency between the happiness of immigrants and the locally born", said Helliwell.
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The US came in at 18th position, down from 14th place in 2017, while Britain ranked 19th and the United Arab Emirates (UAE), 20th.
"The countries with the happiest immigrants are not the richest countries, but instead the countries with a more balanced set of social and institutional supports for better lives", the report states. The top 10 is rounded out by Switzerland, the Netherlands, Canada, New Zealand, Sweden, and Australia.
The 2018 World Happiness Report also charts the steady decline of the United States as the world's largest economy grapples with a crisis of obesity, substance abuse and depression.
Finland took top honours in that category too, giving the country a statistical double-gold status. In reaching No. 1, Finland nudged neighbouring Norway into second place. But the United Nations ranking places the UK in a lowly 19th place, the same as a year ago but behind Germany, Canada and Australia, although ahead of France and Spain. It is based on Gallup International surveys conducted from 2015 to 2017, in which thousands of respondents were asked to imagine a ladder with steps numbered 0 to 10 and to say which step they felt they stood on, a ranking known as the Cantril Scale.
For the first time, this year's study also evaluated happiness from the point of view of migrants in each country.