The United States ranked 19^th in the world for howsecure its citizens are in retirement, according to a new study byNatixis Global Asset Management. The findings suggest thatAmericans will need to pick up a bigger share of their retirementcosts especially as the number of retirees grows and thegovernment’s ability to support them fades.

The Natixis Global Retirement Index gauges how well retiredcitizens live in 150 nations, based on measures of health, materialwell-being, finances and other factors.

The United States ranked slightly ahead of the United Kingdom,but behind Norway, Switzerland, Luxembourg, Sweden, Austria,Finland, Netherlands, Denmark, Germany, France, Australia, Israel,Canada, Belgium, Japan, Slovenia, Czech Republic and Slovakia inthe list’s top 20.

The U.S. is the world’s biggest pension market, but it lagsbehind less-affluent nations on measures of income and health,according to the index. While the U.S. leads the world inper-capita health spending, individuals are still required to pay aportion of this expense on their own. That leaves many health costsin the hands of retirees and takes resources away from their otherneeds.

In contrast, Western European nations backed by robust healthcare and retiree social programs dominate the top of the rankings,taking the first 10 spots

People in the United States will be called on to finance more oftheir retirement, said John Hailer, president and CEO for theAmericas and Asia at Natixis Global Asset Management. Citizens ofother industrialized nations can rely on strong social safety netsin old age, but in the U.S., we encourage workers to plan, save andinvest, and promote policies that help them meet their futureneeds, he said.

The U.S. is facing numerous challenges, including a rapidlyaging population, rising life expectancy and declining birth rates.Globally, the number of people over the age of 65 is on track totriple by 2050. By that time, the working ratio of the working-agepopulation to those over age 65 in the U.S. is expected to dropfrom 5-to-1 to 2.8-to-1.

This will make it hard for the government to finance programslike Social Security and Medicare and will mean a heaving financialburden going forward for individuals saving for retirement.

The U.S. also is encountering a retirement savings deficit of$6.6 trillion or nearly $57,000 per household, according to U.S.Senate figures. As a result, 53 percent of American workers age 30and over will be unprepared for retirement, up significantly from38 percent in 2011.