ANN ARBOR, Mich. -- It may seem hard to believe in these days of economic woe, but a new study finds that people are happier now than they were a quarter century ago.

Researchers from the University of Michigan Institute for Social Research conducted the "World Values Survey" from 1981 to 2007.

They asked 350,000 people in 52 countries if they considered themselves happy, and if they were satisfied with their lives.

The combined responses to the two questions make up the "happiness index."

The new report finds that the index rose in 40 countries, and fell in just twelve.

The "happiest" country in the world was Denmark, and the unhappiest was Zimbabwe. The United States ranked 16th, just after New Zealand.

Researchers from the World Values Survey say economic growth, democratization and rising social tolerance all contributed to the higher rates of happiness around the world.