Overall, about 5% of U.S. students are enrolled in charter schools, but this proportion varies from state to state.
As of 2012-13, 15 states with charter schools had enrollment less than 3%, while 16 states had charter enrollment greater than or equal to 5%. Only 2.2% of New Jersey students and 1.2% of Tennessee students were enrolled in charter schools. Among states with larger charter sectors, 7.6% of students in California and 10.4% in Colorado attended charter schools. Arizona had the highest rate of charter school enrollment, with 13.9% of public K-12 students enrolled in charter schools.
National Center for Education Statistics at the U.S. Department of Education: Public elementary and secondary charter schools and enrollment, by state: Selected years, 1999-2000 through 2012-13