The NSA claims it only looks at 1.6 per cent of internet traffic of which only 0.025 per cent is selected for review. So in other words NSA analysts look at 0.00004 per cent of the world's traffic in conducting their mission. The NSA said that if a standard basketball court represented the global communications environment, NSA's total collection would be represented by an area smaller than a dime.
However it turns out that dime is still 29.21 petabytes of data a day. That means NSA is "touching" more data than Google processes every day. Google only has 20 petabytes. Also the packet analyzer gear at the front-end of XKeyscore (can pick out a very small fraction of the actual packets sent over the wire while still extracting a great deal of information (or metadata) about who is sending what to who.
So while 1.6 per cent was an attempt to make people think this is no big deal it is actually huge. In fact the NSA is telling the world that it may be collecting even more information that people had believed before.