Americans are living longer than ever, but not as long as people in 41 other countries. For decades, the United States has been slipping in rankings of life expectancy, as other countries improve healthcare, nutrition and lifestyles. Countries that surpass the United States include Japan and most of Europe, as well as Jordan, Guam and the Cayman Islands. Something's wrong here when one of the richest countries in the world, the one that spends the most on healthcare, is not able to keep up with other countries," said Christopher Murray, head of the Institute for Health Metrics and Evaluation at the University of Washington. A baby born in the United States in 2004 is expected to live an average of 77.9 years. That ranks 42nd, down from 11th two decades earlier. Andorra, a tiny country between France and Spain, had the longest life expectancy, at 83.5 years, according to the Census Bureau. It was followed by Japan, Macao, San Marino and Singapore. Researchers say several factors have contributed to the United States falling behind other industrialized nations. A major one, they say, is that 47 million people in the United States lack health insurance, whereas Canada and many European countries have universal healthcare. But "it's not as simple as saying, 'We don't have national health insurance,' " said Samuel B. Harper, an epidemiologist at McGill University in Montreal. Among the other factors researchers cite: Adults in the United States have one of the world's highest obesity rates. Nearly a third of those 20 or older are obese, according to the National Center for Health Statistics. "The U.S. has the resources that allow people to get fat and lazy," said Paul D. Terry, an assistant professor of epidemiology at Emory University in Atlanta.