The number of government workers and contractors holding security clearances dramatically decreased last year—a sign that the US government has limited the number of people with access to secrets in the wake of National Security Agency contractor-turned-whistleblower Edward Snowden’s massive unauthorized public disclosure in 2013.

The data, released to Congress by the Office of the Director of National Intelligence (ODNI), shows that roughly 4.5 million people had some form of government security clearance in 2014—a year-over-year decline of more than 600,000 federal employees authorized to handle sensitive information.

Among agencies analyzed by the ODNI, The NSA, unsurprisingly, rejected security clearance requests at the highest rate—9.2 percent.

The National Geospatial-Intelligence Agency (NGA) led the way in revocations, pulling 2.2% of clearances from its workforce.

Although not mentioned in the report, were Snowden’s disclosures, which ratcheted up pressure on the sprawling population of federal employees and contractors with security clearances. When stories based on Snowden’s revelations started making headlines in the summer of 2013, much of the debate focused on the fact that the federal government had given more than 5.1 million of its employees and contractors—a sum constituting roughly 1.5 percent of the entire US population– permission to access some kind of classified material.

In October 2013, the ODNI issued a directive to agency heads to initiate an immediate review of all individuals with clearances.

“Access to classified information is a privilege and the decision to entrust an individual with access to classified information is a critical decision the United State Government takes very seriously,” the directive, written by DNI James Clapper, read.

The report concluded that the DNI’s call for review “was effective,” and resulted in a 15 percent reduction in the population eligible to receive secret clearance in the Department of Defense. In the same time frame, the intelligence community and the rest of the government also saw 1.3 percent and 1.5 percent declines, respectively, in the number of active security clearances they have issued.

The information was released publicly by investigative reporter Steven Aftergood with the Federation of American Scientists, who noted that it was the first time clearances had declined on a year-over-year basis since ODNI began publishing the reports in 2010.