5.1 million Americans have security clearances. That’s more than the entire population of Norway. - The Washington Post

Critics of the country's national security apparatus say Washington is addicted to secrecy. Judging by the ballooning number of Americans with government security clearances, they might have a point.

About 5.1 million people — or more than 1.5 percent of the population — held security clearances last year, up from 4.9 million people with clearances the year before. The new figure comes via a report commissioned by President Obama and released by the Office of Management and Budget, which estimates that 60 percent of those security clearances had immediate access to confidential data.

If the security-cleared population were its own country, it would be bigger than Norway.

Investigating candidates for security clearances also costs a pretty penny; OMB estimates that a background check for a Secret-level clearance costs between $210-$272 for each of the 3.6 million people who have them. A Top Secret clearance, meanwhile, costs the government nearly 20 times more, at an average of $3,959 per background check. At that rate, investigating the 1.5 million people with Top Secret passes may have cost as much as $5.9 billion over several years. And it gets worse: Many of the clearances currently held by federal workers have already expired.

"The most recent data show that roughly 22 percent of the population eligible for access to classified information at the TS or TS/SCI level was outdated, and no reinvestigation had been requested," OMB wrote. Translation: There are people walking around with clearances today who maybe shouldn't have them.

Many background checks are performed each year by a single contractor — U.S. Investigations Services, which was accused in January by the government of submitting hundreds of thousands of incomplete background checks in order to meet demand. The same company was responsible for vetting both former National Security Agency contractor Edward Snowden and Washington Navy Yard shooter Aaron Alexis.

The explosion in security clearances was also likely fueled by America's two most recent wars. From 2005 to 2013, OMB says, the cost of performing background checks for the Pentagon surged 37 percent, from $487 million to $665 million.

After the Sept. 11 terrorist attacks, there was concern that the country didn't have enough manpower to connect the dots on intelligence. Now, the growing army of people with access to private information risks making the nation's secrets less, well, secret.