District of Columbia Public Schools (DCPS), the sole public school district in the city, operates the city's 123 public schools. The number of students in DCPS steadily decreased for 39 years until 2009. In the 2010–11 school year, 46,191 students were enrolled in the public school system. DCPS has one of the highest-cost, yet lowest-performing school systems in the country, in terms of both infrastructure and student achievement. Mayor Adrian Fenty's administration made sweeping changes to the system by closing schools, replacing teachers, firing principals, and using private education firms to aid curriculum development.