"The top five countries all have nearly equally high values for the six factors found to support happiness, and four of these countries - Denmark, Switzerland, Norway and now Finland - have been in first place in the six World Happiness Report rankings since the first report", said report co-editor John Helliwell, a professor emeritus of economics at the University of British Columbia.
This year's report, published six days ahead of World Happiness Day on March 20, also looked at migration within and between countries.
The Nordic nations, none particularly diverse, have dominated the index since it first was produced in 2012. Finland just pipped Norway into the top spot, whilst Denmark, who used to be the clear victor of the annual survey, was reduced to taking home the No. 3 spot on the list.
Rounding out the Top 10 are Denmark, Iceland, Switzerland, Netherlands, Canada, New Zealand, Sweden and Australia.
The United States fell to 18th place from 14th previous year in the index done by the UN Sustainable Development Solutions Network.
Wiking explained that while people in Nordic nations pay some of the highest taxes in the world, that price is well worth it for the levels of personal freedom and social security their countries give them.
'Briefly put, (Nordic countries) are good at converting wealth into well-being, ' Wiking said.
The study found that the 10 happiest countries in the overall rankings also scored highest on immigrant happiness, suggesting that migrants' well-being depends primarily on the quality of life in their adopted home.
"The most striking finding of the report is the remarkable consistency between the happiness of immigrants and the locally born", Helliwell said. "Those who move to happier countries gain, while those who move to less happy countries lose", though the adjustment of happiness is not complete, as migrants still reflect in part the happiness of their birth country. The country also has a socio-economic system which leads to more income equality - a major factor in unhappiness - than other high income nations.
The United States was 11th in the first index and has never been in the Top 10.
"Social support networks in the US have weakened over time", the report said. "The trends are not good, and the comparative position of the US relative to other high-income countries is nothing short of alarming".
"Although immigrants come from countries with very different levels of happiness, their reported life evaluations converge towards those of other residents in their new countries", said Helliwell. Notably, the United States dropped four spots to 18th place.
And if you're wondering what makes Finland so damn happy, then these pictures of the landscape might be an indicator.