The number of American schoolchildren receiving special education services is on the rise.

Newly-released data from the U.S. Department of Education indicates that 6,050,725 students ages 6 to 21 across the country were served under the Individuals with Disabilities Education Act during the 2015-2016 school year.

That’s up from 5,944,241 the prior year, Education Department figures show.

The uptick appears to stem from an increase in the number of children identified with autism, developmental delay and a catch-all category known as “other health impairments.”

At the same time, national totals for kids with intellectual disability, multiple disabilities, the largest category — specific learning disabilities — and several other categories were largely flat.

States and territories regularly report their special education enrollment to the federal government. In addition to information on the total number of students served under IDEA, the Education Department tracks how many kids are classified in each of 13 diagnostic categories.

Data from the 2015-2016 school year is the most recent available.

California had the most students covered by IDEA at nearly 650,000 while North Dakota was the state with the least with fewer than 12,000, according to the Education Department.