The number of American schoolchildren receiving special education services is on the rise and they’re increasingly being served in mainstream classrooms at least part of the day.

More than 6.1 million students across the country ages 6 to 21 — or 9.2 percent of all kids — were served under the Individuals with Disabilities Education Act in 2017, the most recent year for which data is available. That’s up from 8.6 percent of children in 2008.

The figures come from a report to Congress issued this month by the U.S. Department of Education. The agency is required to report annually on its progress implementing IDEA.

Among students in special education in 2017, the largest group — 38.2 percent — had a diagnosis of specific learning disability followed by speech or language impairment, other health impairment, autism and intellectual disability.

The percentage of students identified as having autism rose gradually between 2008 and 2017 across all age groups, the report found. However, the growth was most striking for those ages 18 to 21 who saw more than a 160 percent increase in diagnoses over the time period.

Nearly all students in special education spent some of their day in regular education classrooms in 2017 and the majority spent at least 80 percent of their day there.

Meanwhile, the Education Department reported that the number of students spending less than 40 percent of the day in mainstream environments declined as compared to a decade ago. But, about half of students with intellectual disabilities or multiple disabilities fell into this category.

Graduation rates among special education students are also on the upswing, the report found. Some 70.5 percent of students ages 14 to 21 who exited school did so with a regular diploma compared to just 59 percent for the 2007-2008 school year.

Likewise, the number of students served under IDEA who dropped out of school declined from 24.6 percent to 17.1 percent over the same period, the the Education Department said.

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