In 2005 China has $800B foreign reserve. Now China has $1300B foreign reserve. Between 2005 and now RMB has appreciated 9% against Dollar. During the same time US Treasury yield is about 5% APR. Obviously commodity prices e.g oil, gold, copper, etc. have risen a lot more than 9% during the same period.
Basically the Chinese government has lent the United States $800+ Billion for zero percent interest, if calculated in RMB, for the past two plus years. And negative interest if caculated in gold, oil, or other commodities.
Who can get a better deal than this? :)