[Excerpt] In 1974, the federal government established the Supplemental Security Income (SSI) program to provide cash assistance to people who are disabled, aged, or both and who have low income and few assets. SSI replaced several state-run support programs that had been partially financed by the federal government. In fiscal year 2013, the program will make payments to more than 8 million people at a cost to the federal government of about $53 billion, the Congressional Budget Office (CBO) estimates. Currently, about 60 percent of SSI recipients are disabled adults (ages 18 to 64), about 15 percent are disabled children (under age 18), and about 25 percent are aged adults (age 65 or over) with or without disabilities. SSI recipients generally are eligible for health insurance through Medicaid, and many also participate in other income-security programs that provide federal support to low-income people. In coming years, CBO projects that as the economy improves and average Social Security benefits continue to increase, the number of SSI beneficiaries will decline slightly as a share of the population. In addition, SSI payments per recipient are linked to prices, which tend to rise more slowly than GDP per person. As a result of those two factors, CBO projects that total outlays for SSI will decline slightly relative to total output over the next decade, reaching one-quarter of one percent of GDP.