For the sixth year running, Finland was named the world's happiest country in an annual UN-sponsored index Monday. With thousands of lakes and near endless forests, the Nordic country is known for its extensive welfare system, high trust in authorities and low levels of inequality among its 5.5 million inhabitants.

Northern Europe once again dominated the top spots -- with Denmark in second place followed by Iceland. Knocking France off the 20th spot, Lithuania became the only new country in the top 20 with Estonia in at number 31, up from 66 in 2017.

The World Happiness Report, first published in 2012, is based on people's own assessment of their happiness, as well as economic and social data. The report considers six key factors: social support, income, health, freedom, generosity, and absence of corruption. It assigns a happiness score based on an average of data over a three-year period.