Social support is key to happiness, and the World Happiness Report 2017, released by the Sustainable Development Solutions Network in late March, shows just how important those foundations can be in shaping the overall happiness of a country.

Norway tops the global happiness rankings this year, moving up from 4th place in 2016, followed closely by Denmark, Iceland and Switzerland. All of the top-four ranked countries score highly on the factors found to support happiness: caring, freedom, generosity, honesty, health, income and good governance.

But the report points out that about half of the differences in rankings can be explained by things like having someone to count on, generosity, a sense of freedom and freedom from corruption – all key to strong social foundations. The other half is attributed to GDP per capita and healthy life expectancy – both of which also depend on the social context.

“The Scandinavian countries are very big on social support,” Dr Jan-Emmanuel De Neve, one of the study’s associate editors and a speaker at the 2016 Global Wellness Summit, told Time magazine. “The top countries, you can see, have societies which are not at each other’s throats. But they also have high GDP per capita.”

The US dropped one point this year to number 14, despite increases in income and healthy life expectancy. But the four social rankings – generosity, social support, trustworthy governance and freedom – all dropped, suggesting that American happiness is dwindling primarily due to social causes rather than economic ones.

Mental health is also extremely important to happiness, the report finds. In Western societies, diagnosed mental illness has more of an effect on happiness than income, employment or physical illness. In every country, physical health is also important, yet in no country is it more important than mental health. In all countries, the most powerful effect would come from eliminating depression and anxiety, which are the biggest forms of mental illness.

The report also found that people in China are no happier than they were 25 years ago, and that much of Africa is struggling when it comes to happiness.

The first World Happiness Report was published in 2012. Since then, happiness is increasingly seen as a measure of social progress and a goal of public policy.