The United States is lagging 15 countries in tapping the combined economic value of all of its workers, according to the World Economic Forum’s 2013 Human Capital Index. Switzerland took the top honors as the country that is most efficiently using and developing its human capital.

The economic value of each member of a country’s workforce can be a more important determinant of its long-term success than virtually any other resource, according to WEF’s report, but it can be very difficult to measure.

The WEF looked at four indicators to measure the value of each country’s human capital: education, of the current workforce as well as the educational resources available to the next generation of workers; employment (how well are female workers integrated into the workforce, how does the economy treat its oldest and youngest workers); access to health care; and “enabling environment,” or how each country’s legal structure encourages or discourages entrepreneurial spirit.

Finland, Singapore, Netherlands and Sweden rounded out the top five countries in the index. The countries with the lowest ranks on the Human Capital Index were Yemen, Mauritania, Guinea, Burkina Faso and Mali.

The U.S. ranked 16 of the 122 countries analyzed, and would have ranked even higher if it weren't for its relatively low “health and wellness” rank. While the U.S. ranked high in the “workforce and employment” (4) and in “enabling environment” (9) categories, it ranked 43 in “health and wellness.”

The U.S.' low health rank was attributed to the prevalence of obesity and stress among American workers, Saadia Zahidi, the head of the WEF’s human capital project, told Scientific American. For the U.S., economic growth hinges on improvements in health care, she said.

Here’s an interactive map of the all the countries analyzed by the WEF, color-coded by their rank on the Human Capital Index. Click on any country for more info: