To be slightly more transparent and/or spew numbers to confuse the common citizen, the Obama administration released two documents to show the scope of the NSA's data collection program. Those documents reveal that the NSA monitors 1.6% of the world's Internet traffic and reviews .00004% of all traffic.
Sounds so little, right? Just what the US government wants people to think. Here is the meat of the numbers:
According to figures published by a major tech provider, the Internet carries 1,826 Petabytes of information per day. In its foreign intelligence mission, NSA touches about 1.6% of that. However, of the 1.6% of the data, only 0.025% is actually selected for review. The net effect is that NSA analysts look at 0.00004% of the world's traffic in conducting their mission— that's less than one part in a million. Put another way, if a standard basketball court represented the global communications environment, NSA's total collection would be represented by an area smaller than a dime on that basketball court.
Than a dime on a basketball court! The documents does cite how the program has helped stop a terrorist attacks in 2009 (a New York subway bomb) but it's quite obvious that the NSA is using the specific 1.6% to make their actual number look less. It's still a TON of traffic being monitored given the well, hugeness of the Internet. [NSA via CNN, Verge]