The percentages of households at risk of not having sufficient retirement income to maintain their standards of living remained about flat in 2013 compared with 2010, with the risk for those closest to retirement actually moving up slightly.

The index, crafted by the Center for Retirement Research, uses target income replacement rates for households of different age groups once they hit age 65. It includes income from retirement savings and other sources such as Social Security and annuity benefits. Households whose projected replacement rates fall more than 10 percent the target are deemed to be at risk.

Overall, it said that 52 percent of households were at risk in 2013 compared with 53 percent in 2010, with those in the 30-39 age group falling from 62 to 59 percent, those 40-49 falling from 55 to 52 percent, but those 50-59 rising from 44 to 55 percent.

Importantly for federal employees, who have defined benefit retirement plans, the percentage of households with such plans at risk was only 19 percent in 2010 and 20 percent in 2013.

Factors adding to risk include low interest rates on the type of conservative investments favored by those in or near retirement, while favorable stock market returns worked to reduce risk. Overall, it said, the data “clearly indicates that many Americans need to save more and/or work longer.”