Finland has topped an index of the happiest nations for the second consecutive year, with researchers saying the small Nordic country has succeeded in generating a happiness recipe not simply dependent on economic wealth.

The World Happiness Report, produced by the U.N Sustainable Development Solutions Network, ranks 156 countries by how happy their citizens see themselves to be. It's based on factors including economic wealth, life expectancy, social support and freedom to make life choices.

The index, published Wednesday, showed the other Nordic countries did well, with Denmark, Norway and Iceland taking the next spots.

The United States dropped from the 18th to 19th place.

Happiness has declined the most drastically in the past ten years in the 108th placed Venezuela, currently in political crisis.