HELSINKI (BLOOMBERG) - Finland was once again crowned as the world's happiest country, extending its lead over Denmark and Switzerland, according to a United Nations-affiliated research network.

Finnish contentment stems from high levels of trust, which also underpins solid rankings across the rest of the Nordic region, the Sustainable Development Solutions Network said in the World Happiness Report on Friday (March 20).

Reliable and extensive welfare benefits, low corruption, and well-functioning democracy and state institutions are also key, as are a high sense of autonomy and freedom reported by their citizens.

"The World Happiness Report has proven to be an indispensable tool for policy makers looking to better understand what makes people happy," said Mr Jeffrey Sachs, director of the network.

The results are based on an average of three years of surveys between 2017 and 2019, meaning there's overlap in the data from previous years, and include factors such as gross domestic product, social support from friends and family, healthy life expectancy, freedom to make life choices, generosity, perceived corruption and recent emotions - both happy and sad.

Singapore is ranked No.31, the second happiest behind Taiwan (No.25) in Asia. Japan is No. 62 while Malaysia is No. 82.

Afghanistan ranked lowest among 153 countries, with South Sudan and Zimbabwe just above it. The ranking saw the US rise one place, to 18th.