Quarter	Billions of US Dollars
1997-07-01	0.20000
2004-07-01	-0.20000
2006-10-01	0.25000
2007-01-01	0.43057
2009-01-01	-0.05000
2011-01-01	0.04000
2012-01-01	-0.14682
2012-04-01	-0.20500
2013-04-01	0.00005
2013-10-01	-0.25000
2014-01-01	-0.00005