NEW YORK/LONDON – The world is aging so fast that most countries are not prepared to support their swelling numbers of elderly people, according to a global study released Tuesday by the United Nations and a rights group for the elderly.

The report ranks the social and economic well-being of elders in 91 countries, with Sweden on top, Afghanistan at the bottom and Japan ranked 10th.

It reflects what advocates for the old have been warning for years: Nations are simply not working quickly enough to cope with a population graying faster than ever before. By the year 2050, for the first time in history, seniors over the age of 60 will outnumber children under the age of 15.

Perhaps surprisingly, the report shows that the fastest aging countries are developing ones, such as Jordan, Laos, Mongolia, Nicaragua and Vietnam, where the number of older people will more than triple by 2050. All ranked in the bottom half of the index.

The Global AgeWatch Index — www.globalagewatch.org — was created by advocacy group HelpAge International and the U.N. Population Fund in part to address a lack of international data on the extent and impact of global aging. The index, released on the U.N. International Day of Older Persons, compiles data from the United Nations, the World Health Organization, World Bank and other global agencies, and analyzes income, health, education, employment and how age-friendly the environment is in each country.

The index was welcomed by rights advocates for the elderly who have long complained that a lack of data has thwarted their attempts to raise the issue on government agendas.”Unless you measure something, it doesn’t really exist in the minds of decision-makers,” said John Beard, director of aging and life course for the WHO. “One of the challenges for population aging is that we don’t even collect the data, let alone start to analyze it. . . . For example, we’ve been talking about how people are living longer, but I can’t tell you people are living longer and sicker, or longer in good health.”

The report fits into an increasingly complex picture of aging and what it means to the world. On the one hand, the fact that people are living longer is a testament to advances in health care and nutrition, and advocates emphasize that the elderly should be seen not as a burden but as a resource. On the other, many countries still lack a basic social protection floor that provides income, health care and housing for their senior citizens.

Afghanistan, for instance, offers no pension to those not in the government. Life expectancy is 59 years for men and 61 for women, compared to a global average of 68 for men and 72 for women, according to U.N. data.

That leaves Abdul Wasay struggling to survive. At 75, the former cook and blacksmith spends most of his day trying to sell toothbrushes and toothpaste on a busy street corner in Kabul’s main market. The job nets just $6 a day — barely enough to support his wife. He can only buy meat twice a month; the family relies mainly on potatoes and vegetables.

“It’s difficult because my knees are weak and I can’t really stand for a long time,” he said. “But what can I do? It’s even harder in winter, but I can’t afford treatment.”

Although government hospitals are free, Wasay complained that they provide little treatment and hardly any medicine. He wants to stop working in three years, but is not sure his children can support him. He said many older people cannot find work because they are not strong enough to do day labor, and some resort to begging.

“You have to keep working no matter how old you are — no one is rich enough to stop,” he said. “Life is very difficult.”

Many nations have resisted tackling the issue partly because it is viewed as hugely complicated, negative and costly — which is not necessarily true, according to Silvia Stefanoni, chief executive of HelpAge International. Japan and Germany, she pointed out, have among the highest proportions of elderly citizens in the world, but also boast steady economies.

“There’s no evidence that an aging population is a population that is economically damaged,” she said.

Stefanoni said Japan’s position reflects long-term investment in providing facilities for the elderly.

“As the country with the highest proportion of older adults — 30 percent of people in Japan are over 60 — Japan has recognized the challenge of population aging, and has taken a long-term approach to supporting people as they age with good laws and policies and innovative technologies,” Stefanoni said.

Japan scored particularly well on income and life expectancy.

“We hope its high position in the index will encourage other fast-aging countries to take heed of the lessons which Japan has learned,” she said. “Japan has found innovative ways to deal with problems such as rising long-term care costs by incorporating disability prevention services . . . and the promotion of independent living.”

Prosperity in itself does not guarantee protection for the old. The world’s rising economic powers — the so-called BRICS nations of Brazil, Russia, India, China and South Africa — rank lower in the index than some poorer countries, such as Uruguay and Panama.

However, the report found, wealthy nations are in general better prepared for aging than poorer ones. Sweden, where the pension system is 100 years old, made the top of the list because of its social support, education and health coverage, followed by Norway, Germany, the Netherlands and Canada. The U.S. came in eighth, with Britain 13th.

Sweden’s health system earned praise from Marianne Blomberg, an 80-year-old Stockholm resident. “The health care system, for me, has worked extraordinarily well,” she said. “I suffer from atrial fibrillation and from the minute I call emergency until I am discharged, it is absolutely amazing. I can’t complain about anything — even the food is good.”

Still, even in an elderly-friendly country such as Sweden, aging is not without its challenges.

The Swedish government has suggested people continue working beyond 65, a prospect Blomberg cautiously welcomes but warns should not be a requirement. She also criticized the nation’s finance minister, Anders Borg, for cutting taxes sharply for working Swedes but only marginally for retirees.

“I go to lectures and museums and the theater and those kinds of things, but I probably have to stop that soon because it gets terribly expensive,” Blomberg said. “If you want to be active like me, it is hard. But to sit home and stare at the walls doesn’t cost anything.”