Finland has been crowned the happiest country in the world for the second year in a row, leading a top ten that is made up of five Nordic nations.

The World Happiness Report, released today, ranked 156 countries by happiness levels, based on factors such as life expectancy, social support and corruption.

But while the Nordic nations of Finland, Norway, Denmark, Sweden and Iceland topped the table, there was no sign of Britain in the top ten.

Fans of skiing, saunas and Father Christmas won't be surprised to hear Finland has been named the happiest place to live in the world for the second year in a row. Its capital Helsinki is shown in this file picture

The UK placed 15th, up from 19th last year, one above Ireland and four above the US - which came in at its lowest ranking ever at 19th.

But Britain still trailed behind the likes of Israel, Austria, Costa Rica, Australia, Luxembourg, Canada and New Zealand.

The North African nation of South Sudan was at the bottom of the happiness index which found America was getting less happy each year even as the country became richer - falling from 14th place in two years.

It is the second year the U.N. Sustainable Development Solutions Network evaluated 117 countries by the happiness and well-being of their immigrants as part of the annual report.

Europe's Nordic nations, none particularly diverse, have dominated the index since it first was produced in 2012.

Finland took the top spot with a score of 7.769 out of ten, beating second-placed Denmark which scored 7.6.

Filling out the top five was Norway in third, with 7.554 and Iceland fourth, scoring 7.494, narrowly ranking above fifth-placed Netherlands with 7.488.

Propping up the table was South Sudan, with a score of just 2.853. The bottom ten also included Central African Republic, Afghanistan, Tanzania, Rwanda, Yemen, Malawi, Syria, Botswana, Haiti and Zimbabwe.

Meanwhile Russia was 68th - down from 59th - France 24th and China 93rd.

Relatively homogenous Finland has about 300,000 foreigners and residents with foreign roots, out of its 5.5 million people.

Its largest immigrant groups come from other European nations, but there also are communities from Afghanistan, China, Iraq and Somalia.

Meik Wiking, CEO of the Copenhagen-based Happiness Research Institute, said the five Nordic countries that reliably rank high in the index 'are doing something right in terms of creating good conditions for good lives,' something newcomers have noticed.

He said the happiness revealed in the survey derives from healthy amounts of both personal freedom and social security that outweigh residents having to pay 'some of the highest taxes in the world.'

'Briefly put, (Nordic countries) are good at converting wealth into well-being,' Wiking said. The finding on the happiness of immigrants 'shows the conditions that we live under matter greatly to our quality of life, that happiness is not only a matter of choice.'

Four different countries have held top ten spots in the five most recent reports- Denmark, Switzerland, Norway and now Finland.

All the top countries tend to have high values for all six of the key variables that have been found to support well-being: income, healthy life expectancy, social support, freedom, trust and generosity.

South Sudan, which has been wracked by five years of civil war that has killed as many as 400,000 people, ranked last in the index

The US was 11th in the first index and has never been in the top ten. Jeffrey D. Sachs, Director of Center for Sustainable Development at Columbia University, explained this citing several factors.

He said: 'The long-term rise in U.S. income per person has been accompanied by several trends adverse to subjective well-being (SWB): worsening health conditions for much of the population; declining social trust; and declining confidence in government.

'Whatever benefits in SWB might have accrued as the result of rising incomes seem to have been offset by these adverse trends... [It's] apparently due in part to the astoundingly large amount of time that young people are spending on digital media: smartphones, videogames, computers, and the like.

'The prevalence of addictions in American society seems to be on the rise, perhaps dramatically... They include gambling; social media use, video gaming, shopping, consuming unhealthy foods.

'These addictions, in turn, seem to be causing considerable unhappiness and even depression.'