Quarter	Millions of US Dollars
1982-10-01	12
1992-10-01	-24
1997-04-01	50
1998-10-01	65
2000-04-01	-50
2002-07-01	350
2004-10-01	100
2007-10-01	500
2008-10-01	-65
2009-10-01	400
2010-10-01	1000
2011-07-01	1000
2012-04-01	500
2012-07-01	1000
2012-10-01	-500
2013-04-01	500
2013-07-01	750
2013-10-01	100
2014-01-01	1000
2014-04-01	675
2014-07-01	250
2015-01-01	-500
2015-04-01	650
2015-10-01	1500
2016-07-01	1500
2017-04-01	1000
2018-04-01	3250