Nigeria Ranks 78 on the list of the happiest countries in the world as Togo comes last.

There's a new World Happiness Report out this week that ranks the most cheerful nations in the world.

Switzerland ranks No. 1, trailed by Iceland, Denmark, Norway, Canada, Finland, the Netherlands and Sweden. America ranks 15th, a slight improvement from last year. The saddest — er, least "happy" — countries include Togo, Burundi, Syria, Benin and Rwanda. See charts after the cut.

Data, which can be used to guide policy, is based on research collected by economists and scientist analyzing the factors that make people feel satisfied. Data points include life expectancy, freedom to make life choices and social support. 

Here's the rundown of the world's top 20 happiest countries:

Nigeria ranks 78 in the just concluded study.

Nigeria ranks 78 in the just concluded study.

Togo Burundi and Syria come last on the list

Nigeria ranking 25th in the 2005 - 2007 study

Nigeria ranking 25th in the 2005 - 2007 study