what percentage of us treasury investments are owned by china?

Answer 1

http://www.bullandbearwise.com/TreasuryOwnership.asp
- graph showing US debt ownership categorized between the gov't, priv. dom., and priv. for. owners.
http://www.fms.treas.gov/bulletin/b2006-4fd.doc
-more detailed chart of debt progression and claims
http://www.thetrumpet.com/index.php?page=article&id=2265
-an article summarizing debt ownership

The American populace is the greatest backer of American debt in spite of all you hear about how China, Japan, and the UK are owed so much. Moreso, if these countries were to call in their debt, we could do the same which would cripple their economies.