Students with disabilities in grades K-12 identified as having disabilities under IDEA represent 8.4% of all students enrolled in public education. Disability categories children are often placed in and national percentages for the 2011-12 school year were as follows:

Source: Thirty-fifth Annual Report to Congress on Implementation of the IDEA, US Department of Education. Washington DC, 2013
Specific learning disabilities 41%
Speech or language impairments 19%
Other health impairments 13%
Autism 7%
Intellectual disabilities 7%
Emotional disturbance 6%
Developmental delay 2%
Multiple disabilities 2%
Hearing impairments 1%
Orthopedic impairments 1%
Deaf-blindness <0%
Traumatic brain injury <0%
Visual impairments <0%