This week's revelations about the National Security Agency's hyperactive interest in seeing what's happening online probably inspired you to wonder how much that privilege is costing you.

The very short answer is: We have no idea. The NSA, being a secret agency, doesn't share details about how much money it spends. Basic details about the government organization (like budget and staff size) are classified.

But we can guess. Each month, the Treasury Department releases a statement outlining how much various government divisions and organizations have spent. Over the past six months, here's what spending in the Department of Defense, the NSA's umbrella agency, has looked like.

The Monthly Treasury Statement allows us to dive a little deeper. It breaks out several of the categories above into (very, very large) subcategories: Army, Navy, Air Force, and Defense Agencies. That last category apparently includes the NSA.

So far this year, here's how much each of those divisions has spent this year. The Armed Services branches are responsible for well over 90 percent of the department's personnel spending. But the agencies — which also includes other organizations, like the Defense Intelligence Agency — are responsible for nearly a third of spending on construction. (See also.)

In these five categories, the agencies comprise 17 percent of the spending. If that ratio applies to Defense spending on the whole, those agencies cost $7,907,380,000 in April — nearly eight billion.

In that first graph, you'll notice that April spending is lower than at the end of last year. The Defense Department spent about five percent less this April than it did in April 2012. That's likely due, in part, to the sequestration. While the Office of Management and Budget's detailed list of expected sequestration cuts doesn't mention the NSA, last December an agency representative indicated that he expected to see an effect, as Federal Times reported.

“It will affect all of us — absolutely all of us,” said Chris Inglis, deputy director of the National Security Agency, a part of the Defense Department responsible for electronic eavesdropping abroad on would-be adversaries. While agency officials are working through their options, Inglis said, “it’s too soon to tell” what the potential impact would be.

And in March, Fox News detailed how intelligence agencies planned to respond to the need to temporarily furlough employees.

Intelligence officials are arguing that a certain number of workers are needed in order to adequately monitor and protect the U.S. from national security threats. Officials will not say, however, how many intelligence workers across the Defense Department or government-wide will be exempt.

The U.S. intelligence community is made up of 16 different organizations, ranging from the CIA and the Defense Intelligence Agency to the highly secretive National Security Agency and the National Reconnaissance Office. Altogether the agencies have about 100,000 workers.

(That month, Congress also approved an additional $10 billion in spending, which reduced the need for furloughs and may help account for the blip on the first graph.)

So here's what we know: The NSA probably costs tens or hundreds of millions of dollars a month. It probably lost some funding in the sequestration. Anything beyond that is hard to tell. After all, it's not like we get to monitor their credit card transactions.

Photo: NSA headquarters, via Wikipedia.