From Department of Education, 41st Annual Report to Congress on the Implementation of the Individuals with Disabilities Education Act, 2019:
Between 2008 and 2016, the percentage of the resident population ages 6 through 21 served under IDEA, Part B, that was reported under the category of autism increased gradually from 0.4 percent to 0.9 percent, where it remained in 2017. Between 2008 and 2017, the percentages of the populations ages 6 through 11, 12 through 17, and 18 through 21 served under IDEA, Part B, that were reported under the category of autism all increased. Specifically, the percentages of these three age groups that were reported under the category of autism were 86.1 percent, 147.8 percent, and 163.2 percent larger in 2017 than in 2008, respectively
