Staying healthy and happy is a struggle for about half of Americans, according to a massive survey that attempts to measure the nation's general welfare, much like the Dow Jones Industrial Average portrays the health of the stock market.

The Gallup-Healthways Well-Being Index, based on interviews of more than 100,000 people so far, shows that 47 percent of Americans are struggling and 4 percent are suffering. Forty-nine percent of respondents are reported to be thriving based on a personal assessment of how they feel about their lives at the time of the survey, and where they think they'll be in five years.

Pollsters asked people to imagine where they would put themselves on a ladder with 10 steps. Those said they were on step seven or above are listed as thriving. Those at four or below are suffering. In between are the strugglers.

Those who are thriving tend to have higher incomes, more education and less illness. Those who are suffering have trouble meeting their basic needs, including food, shelter and medical care, said James Harter, Gallup's chief scientist for workplace management and well-being.

Just as the U.S is not No. 1 when it comes to health measures, it also is not No. 1 in well-being, he said. For example, 83 percent of the residents of Denmark are classified as thriving versus 1 percent who are suffering.

Researchers hope the findings, which can be broken down by occupation, commute time and exercise habits, will help employers better understand what they can do to create happier and healthier workers.

Eventually, they said, the data could even be used to compare health and happiness by ZIP code, creating quite a measuring stick for future generations of politicians.

"There's never been anything quite like it," said Daniel Kahneman, a Nobel Prize winner in economic sciences.

"You're getting details about what it's like to live in this country," said Kahneman, a Princeton University professor brought in by Gallup to discuss the potential uses for the data. "What is the experience of the weekend? What is the experience of the weekday for someone who is sick and has to go to work in the morning? We are going to learn a great deal about what are the determinants of actual happiness."

Dr. Julie Gerberding, director of the federal Centers for Disease Control and Prevention, noted that the United States invests more on health care than any country, but that its health care system ranks 37th.

"That doesn't sound like we're getting the best value from the investment we're making," Gerberding said. "That fundamentally is something we as a nation are waking up to."

The research has implications for employers who want to stay on top of problems confronting a particular work force.

The survey shows that manufacturing or transportation workers are most likely to report a negative work environment _ 29 percent. Those who report a negative work environment tend to miss more days of work. A worker with up to three chronic conditions and a negative work environment will miss an average of 6.6 more days of work a year than a similar worker who likes his or her work environment, the survey found.

The survey said a negative work environment includes job dissatisfaction, an authoritative boss, lack of trust and lack of focus on individual strengths.

Among all workers, two-thirds reported one or more chronic diseases or recurring conditions. More than a quarter reported back or neck problems; 23 percent cited high cholesterol and 22 percent had high blood pressure. More than one in 10 said they suffered from depression.

Nearly two-thirds of workers reported body mass indexes indicating they could be obese or overweight.

Healthways, which works with companies to improve the health of workers, partnered with Gallup to pay for the survey. The cost of maintaining the index is projected at more than $20 million annually. More than 1,000 are being interviewed daily.

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On the Net:

Gallup: http://www.gallup.com

Healthways: http://www.healthways.com