The United States lagged in both measures, with 5.8 times annual earnings for men and 6.8 for women. Countries with higher-than-average gross pension wealth include Spain, Switzerland, Saudi Arabia, Argentina, the Netherlands, Greece, Iceland and Luxembourg.
In another measure, the OECD took weighted averages of various indicators and found the pension level for men across the 34 member countries is 55.3% of economy-wide average earnings. The U.S. figure is 37.5%.
US gets a 'C' grade
The 2011 Melbourne Mercer Global Pension Index, released last fall, compared countries' retirement income systems while acknowledging the complexities in doing so.
Countries were graded on a scale from A (the best) to E (the worst), and no country received an A or an E. The United States, along with France, Singapore, Brazil, Poland and Germany, received a C.
A country given a C has "a system that has some good features, but also has major risks and/or shortcomings that should be addressed," the report states. "Without these improvements, its efficacy and/or long-term sustainability can be questioned."
The United States ranked close to average among 16 countries in adequacy of benefits provided and above average in sustainability, the likelihood that the system can maintain the benefits in the future. It fell short, however, on a sub-index focused on the private sector pension system.
The U.S. could take steps for a better score, the report said, including raising the minimum benefit for low-income retirees, improving benefits vesting and further limiting access to funds before retirement.
More from CNBC.com:



