As the U.S. marks the 22nd anniversary of the Americans with Disabilities Act, new Census data indicates that the number of people with disabilities is on the rise.

In a report released Wednesday, the federal agency found that 56.7 million people had a disability in 2010, an increase of 2.2 million since 2005.

Despite the growth in disability prevalence, however, the percentage of people with impairments remained relatively unchanged at 18.7 percent, accounting for roughly 1 in 5 Americans.

About 1.2 million adults had an intellectual disability, according to the report. Meanwhile, some 944,000 adults had other developmental disabilities including autism and cerebral palsy.

Among children, the Census found that 1.7 million kids had an intellectual or developmental condition.

The new Census data marks the first time since 2005 that the agency has offered estimates and analysis on the population of Americans with disabilities, officials said.

Several agencies including the Social Security Administration, Centers for Medicare and Medicaid Services and the Administration on Aging rely on Census data in their planning.