According to this BBC article, Denmark is the world's most happy nation, Zimbabwe the least.
Of course all this needs to be qualified. This information comes from the 97 nations that participated in the U.N.'s World Values Survey, which "asked people two simple questions about their happiness and their level of satisfaction with life."
What two simple questions could sum this up for a nation? At this level of abstraction, it could be any two questions, really.
1) If you could put together your perfect dinner party, whom would you invite (since this question is hypothetical, you are welcome to choose deceased personalities)?
2) Would you serve Gandhi chicken or beef?
But no, the questions were obviously such that a Dane would answer "happy" and a Zimbabwean (Zimbabois? Zimbamboodle?) "unhappy." How about
How do you celebrate a national election?
How do you feel about Greenland actually turning green, thanks to global warming?
It seems like the World Values Survey is just an excuse to make up discussion starters for sleepovers. (We'll see once I can actually get to the site.)