The Transportation Security Agency, created after the 9/11 terrorist attacks in 2001, establishes standards for airport security and directly hires and manages airport security screening personnel at most of the nation's airports. However, 16 of the nation's airports contract with private companies to provide airport security screening with certified inspectors operating under federal standards. These airports participate in TSA's Screening Partnership Program which was established to test whether private contractors could provide the same level of security as federal employees but at cheaper cost. The demonstration program proved to be an outstanding success. Private security screeners at the San Francisco International Airport are 65 percent more efficient than their federal counterparts at the Los Angeles International Airport, according to one study. Despite the success of the alternative program, TSA officials tried to block new airports from using contracted screeners in 2011. Critics contend that agency opposition to private screeners results from empire-building, given that TSA has more than 61,000 staff and has spent more than $2 billion on recruitment and training. Expanding the Screening Partnership Program to the Nation's 35 largest airports could potentially save up to $1 billion over the next ten years in lower TSA personnel costs if the efficiencies found at the San Francisco airport are duplicated at locations serving 75 percent of the nation's air travelers. More airports participating in the Screening Partnership Program will significantly reduce the TSA workforce.