What is the name of the study on people’s happiness in different countries?

Do you live in a happy country? Chances are strong that you do. Results of a recent study have shown that many people around the world are happier now than in the past. The study is called the World Values Survey. Researchers responsible for the study are based at the University of Michigan Institute for Social Research in the United States.
    The researchers gathered information from opinion studies done in more than ninety countries or territories. Those studies were completed between nineteen eighty-one and two thousand seven. More than three hundred fifty thousand people told how happy or unhappy they were feeling. They also said how generally satisfied or unsatisfied they felt.
    The results were reported in the publication "Perspectives on Psychological Science."
    University of Michigan political scientist Ronald Inglehart directed the World Values Survey. Mister Inglehart says the results surprised him. He said it is widely believed that it is nearly impossible for happiness levels for a whole country to improve. He said many earlier studies have suggested that happiness levels do not really change.
    Denmark was found to be the world’s happiest country. Mister Inglehart notes that Denmark’s health care is good and few Danes are hungry. Zimbabwe was rated as the least happy country. Zimbabweans have suffered from political and social unrest.
    Other nations in the top ten for happiness include Iceland, Switzerland, the Netherlands, Canada and Colombia. Colombia suffers from violence in some areas. But Mister Inglehart says Colombians share strong family, friendship and religious ties. He says those qualities are common in areas along the Caribbean Sea. And he says they help balance economic and political weakness. Also, America’s Central Intelligence Agency says the Colombian government has been working harder to control the violence.