The New Economics Foundation looked at 143 countries that are home to 99 percent of the world's population and devised an equation that weighed life expectancy and people's happiness against their environmental impact.

By that formula, Costa Rica is the happiest, greenest country in the world, just ahead of the Dominican Republic.

Latin American countries did well in the survey, occupying nine of the top 10 spots.

Australia scored third place, but other major Western nations did poorly, with Britain coming in at 74th place and the United States at 114th.

The New Economics Foundation's measurements found Costa Ricans have a life expectancy of 78.5 years, and 85 percent of the country's residents say they are happy and satisfied with their lives.

Those figures, taken along with the fact that Costa Rica has a small "ecological footprint," combined to push the small nation to the top of the list.

A 2006 New Economics Foundation study designated Vanuatu the world's happiest nation, with Costa Rica at second place.

Sociologist Andrea Fonseca said Costa Rica gives its citizens the "tools" to be happy, but cautioned that happiness cannot be calculated just by looking at life expectancy and environmental practices.

She added that the country's rise to the top of the Happy Planet Index "has a lot to do with social imagination."

Costa Rica has a peaceful reputation because it does not have an army, and is also known for its protected ecological zones and national slogan "pure life," she said.

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