I really wish you would have just read the article. 

I didn't want to clip and paste other peoples work, but this is why I addressed it to you:

"Another way of visualizing this is how many assets as a percentage of US GDP the Fed will hold on its books. Currently, this number is 18%. By the end of 2013, the Fed's historical flow operations will be accountable for 24% of US GDP.

Why is this important? Simple: when the time comes for the Fed to unwind its balance sheet, if ever, the reverse Flow process will be responsible for deducting at least 24% of US GDP at the time when said tightening happens. If ever."