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A young boy smiles in Dublin, Ireland on March 17, 2012. A new study by the U.N. took happiness of countries into account for the first time. - 

So the first ever World Happiness Report by the U.N. and Columbia's Earth Institute is out, and guess who tops the list? Denmark, Norway and Finland. The least happy countries included Togo, Sierra Leone and Benin.

The results are in line with previous studies done by Gallup and others, but why did the UN start to worry about overall happiness this year?

Here to talk with us is Richard Layard, who co-authored the study.

Follow Jeremy Hobson at @jeremyhobson