More than 400 new public charter schools opened in the 2009-2010 school year according to the National Alliance for Public Charter Schools. This brings the total number of operating charter schools to more than 4900 nationwide and the number of students attending these charter schools to 1.5 million.
Back in 1997 at the first National Charter School Conference everyone was abuzz about the Clinton Administration's goal to have 2,000 charter schools by 2000. Don't know that we met that goal in 2000, but it was hard to imagine so many charter schools at the time when only a couple of hundred people were attending the charter conference and involved in charter school operation.
Back in 1997, Colorado had 52 operating charter schools and this year tops 160 operating schools. Today's percentage of students attending a public charter schools is around 8% or 66,000 students.
Note: I don't know where the Alliance got their data from since it doesn't match CDE data.