A new study of more than 65 countries published in the UK's New Scientist magazine suggests that the happiest people in the world live in Nigeria - and the least happy, in Romania.
People in Latin America, Western Europe and North America are happier than their counterparts in Eastern Europe and Russia.
Nigeria has the highest percentage of happy people followed by Mexico, Venezuela, El Salvador and Puerto Rico, while Russia, Armenia and Romania have the fewest.
But factors that make people happy may vary from one country to the next with personal success and self-expression being seen as the most important in the US, while in Japan, fulfilling the expectations of family and society is valued more highly.
The survey appears to confirm the old adage that money cannot buy happiness.

The researchers for World Values Survey described the desire for material goods as "a happiness suppressant".
They say happiness levels have remained virtually the same in industrialised countries since World War II, although incomes have risen considerably.
The exception is Denmark, where people have become more satisfied with life over the last three decades.
The study was carried out in 1999-2001 and published for the first time by New Scientist this week.
Consumerism
Researchers believe the unchanging trend is linked to consumerism.
"New Zealand ranked 15 for overall satisfaction, the US 16th, Australia 20th and Britain 24th - although Australia beats the other three for day-to-day happiness," New Scientist says.
The survey is a worldwide investigation of socio-cultural and political change conducted about every four years by an international network of social scientists.
It includes questions about how happy people are and how satisfied they are with their lives.
Although such surveys are not new, they are being increasingly taken into account by policy makers, the magazine says.

http://news.bbc.co.uk/1/hi/world/africa/3157570.stm