The NSA's vaunted cell phone metadata collection program, often defended on the grounds that its comprehensive sweep of information allows the government to uncover unseen connections, only collected about 30 percent of all such information as of last summer.

Lost in the pre-Christmas blur was an NBC News interview with one of the members of the group President Obama tasked with reviewing the government's surveillance toolkit. In that interview, Geoffrey Stone suggested that the agency's metadata collection was deliberately incomplete. "Asked if the NSA was collecting the records of 75 percent of phone calls, an estimate that has been used in briefings to Congress," NBC's Michael Isikoff reported, "Stone said the real number was classified but 'not anything close to that' and far lower."

Now The Washington Post puts a number on that: 30 percent.

In 2006, the officials said, the NSA was collecting nearly all records about Americans’ phone calls from a number of U.S. companies under a then-classified program, but as of last summer that share had plummeted to less than 30 percent.

There are a few reasons offered for the gap. One rationale offered from "industry officials" is that the increase in internet-based calling would mean that the NSA loses a significant portion of calls. Stone suggested another reason: culling records from smaller cell phone providers wasn't "cost effective" for the agency, so it didn't bother.

That smaller footprint would apparently also surprise Edward Snowden, the leaker that prompted new scrutiny of the surveillance programs. In an opinion piece last October, Snowden wrote that "no telephone in America makes a call without leaving a record with the NSA." Perhaps his use of "telephone" is suggestive, but even that appears to be overly broad.

Metadata collection, authorized under the secret FISA Court's interpretation of amendments to the Patriot Act, has been defended for what it theoretically offers the NSA: the ability to trace any call between a terror target and other people. "There is no other way we know of to connect the dots," NSA head Keith Alexander told a Senate panel. Without every call being in that database, though, that becomes obviously less effective. You can't connect dots you don't see. And if the agency has decided that ensuring it has all of those dots isn't cost effective, it raises the question of how great the need for any such data actually is.

To The Post, NSA Deputy Director Rick Ledgett used the better-than-nothing excuse. "It’s better than zero. If it’s zero, there’s no chance" of catching terror plots. Which, of course, is a defense that holds up for any information collected in any format forever.