Source: Human Rights Watch, 2009
From the summary:
In this 70-page report, the ACLU and Human Rights Watch found that students with disabilities made up 18.8 percent of students who suffered corporal punishment at school during the 2006-2007 school year, although they constituted just 13.7 percent of the total nationwide student population. At least 41,972 students with disabilities were subjected to corporal punishment in US schools during that year. These numbers probably undercount the actual rate of physical discipline, since not all instances are reported or recorded.