http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp Department of Education data http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp Department of Education data http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp Department of Education data http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp average of less than $47,000 in the 2009-2010 school year http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp Digest of Education Statistics http://nces.ed.gov/programs/digest/d10/tables/dt10_083.asp