A new study finds that people in nations where the population is aging less swiftly, such as the U.S, are less likely to be worried about their old-age futures than those in parts of Europe and East Asia that are grappling with swiftly shrinking workforces and increasing pension costs. The survey by the Pew Research Center covers 21 nations. AP reported that changes in the world's demographics "could alter the distribution of global economic power over the coming decades," Rakesh Kochhar, a senior researcher at Pew, said Thursday. "Demographically, at least, America is poised to maintain its global status while many European and East Asian nations shrink either in absolute or relative terms. India and several African nations may benefit from the projected demographic trends," Kochhar said. "Immigration is the main reason why population growth in the U.S. will be much greater than in Europe or East Asia." Just 26 percent of Americans said aging in their country is a "major problem," according to the report released Thursday. Concern about aging was highest in Asia - 87 percent in Japan, 79 percent in South Korea and 67 percent in China. In Europe, more than half of those surveyed in Germany and Spain pointed to increases in the older population as a major problem in their countries. Americans were relatively optimistic that they will have an adequate standard of living in their old age. About 63 percent of those surveyed said they were "very confident" or "somewhat confident" about their retirement security. They ranked near the top along with other countries with younger populations or strong economies: China, Brazil, Nigeria, South Africa, Kenya and Pakistan. According to the Pew survey, retirement security confidence was lowest in Japan, Italy and Russia. Because of high rates of immigration, America has one of the higher birth rates in the developed world. Its population is expected to rise by 89 million, to 401 million, from 2010 to 2050, with immigrants and their descendants accounting for about 80 percent of the increase. China, currently the most populous nation at 1.4 billion, is projected to add only 25 million people by 2050. Global aging is driven by social and economic factors. Compared to previous decades, marriage rates in general have fallen and birth rates have dropped. Also playing a role in declining births are the rising costs of raising children, increases in women who attend college and are in the labor force as well as the reduced need for children to care for parents in old age. Globally, the median age will rise from 29 to 36 by midcentury. That's faster than the U.S. increase from 37 to 41. -- SPA 23:36 LOCAL TIME 20:36 GMT تغريد