Quarter	Millions of US Dollars
1997-07-01	150
2001-10-01	325
2003-07-01	300
2004-10-01	330
2007-07-01	-150
2011-10-01	-325
2012-04-01	700
2013-01-01	700
2013-07-01	-300
2016-04-01	700
2017-04-01	500