Quarter	Millions of US Dollars
1976-04-01	24
1986-04-01	-24
1989-04-01	16
1992-04-01	30
1993-04-01	-19
1996-04-01	-33
1999-10-01	400
2005-07-01	-400
2006-07-01	254
2006-10-01	66
2010-10-01	200
2011-04-01	200
2011-07-01	-282
2011-10-01	-67
2012-10-01	1200
2013-04-01	2050
2013-07-01	450
2013-10-01	500
2014-04-01	1000
2014-07-01	460
2014-10-01	500
2015-01-01	328
2015-10-01	335
2016-01-01	878
2016-10-01	306
2017-07-01	500
2017-10-01	700
2018-04-01	-500