Twenty-nine percent of U.S workers between 55 and 64 years old have no retirement savings or pension plan, according to a report by the U.S Government Accountabilty Office.

The report also found that 48 percent of pre-retirees have no IRA or 401(k) savings plans, while 20 percent have only a defined-benefit pension plan.

The report represented a slight improvement in U.S. workers' retirement readiness from a similar study done in 2015, when 52 percent were reported to have had no 401(k) or IRA savings plans. The previous report also had 29 percent of retirees with no retirement savings

In addition, the previous report said 26 percent had a retirement savings but no defined-benefit plan and 26 percent had retirement savings and a defined-benefit plan.

Among those with retirement savings, the median amount was about $104,000 for households age 55 to 64 and $148,000 for households age 65 to 74, equivalent to an inflation-protected annuity of $310 and $649 per month, respectively, the report said.

The GAO noted that Social Security provides most of the income for about half of households age 65 and older.

The data used for the GAO study included Federal Reserve household financial data, academic studies of retirement savings adequacy, analyzed retirement-related questions from surveys and interviews with retirement experts about retirement readiness.