their areas, though the average figure is controversial because some charter schools do not enroll a proportionate number of students that require special education or student support services. Additionally, some charters are not required to provide transportation and nutrition services. The Federal Elementary and Secondary Education Act, Part B, Sections 502–511 authorizes funding grants for charter schools. In August 2005, the Thomas B. Fordam Institute, a pro-charter group, published a national report of charter school finance. It found that across 16 states and the District of Columbia—which collectively enrolled 84 percent of that year's one million charter school students—charter schools receive about 22 percent less public funding per-pupil than the district schools that surround them, a difference of about $1,800. For a typical charter school of 250 students, that amounts to about $450,000 per year. The study asserts that the funding gap is wider in most of twenty-seven urban school districts studied, where it amounts to $2,200 per student, and that in cities like San Diego and Atlanta, charters receive 40% less than traditional public schools. The funding gap was largest in South Carolina, California, Ohio, Georgia, Wisconsin and Missouri. The report suggests that the primary driver of the district-charter funding gap is charter schools' lack of access to local and capital funding. A 2010 study found that charters received 64 percent of their district counterparts, averaging $7,131 per pupil compared to the average per pupil expenditure of $11,184 in the traditional public schools in 2009/10 compared to $10,771 per pupil at conventional district public schools. Charters raise an average of some $500 per student in additional revenue from donors. However, funding differences across districts remain considerable in most states that use local property taxes for revenue. Charters that are funded based on a statewide average may have an advantage if they are located in a low-income district, or be at a disadvantage if located in a high-income district. Virtual charter schools In November 2015, the first major study into online charter schools in the United States, the National Study of Online Charter Schools, was published. It found "significantly weaker academic performance" in mathematics and reading in such schools when they were compared to conventional ones. The study was the result of research carried out in 17 US states which had online charter schools, and was conducted by researchers from the University of Washington, Stanford University and Mathematica Policy Research.