Finland has been ranked as the world's happiest country for the eighth successive year, with experts citing access to nature and a strong welfare system as factors.
It came ahead of three other Nordic countries in this year's UN-sponsored World Happiness Report, while Latin America's Costa Rica and Mexico entered the top 10 for the first time.
Both the UK and the US slipped down the list to 23rd and 24th respectively - the lowest-ever position for the latter.
The study also found strangers are about twice as kind as people think. It measured trust in strangers by deliberately losing wallets, seeing how many were returned and comparing that with how many people thought would be handed in.
