Quarter	Millions of US Dollars
1973-07-01	25
1988-07-01	-25
1993-07-01	150
1994-07-01	45
1994-10-01	-45
1996-04-01	191
1997-10-01	150
1998-07-01	-150
2003-07-01	43
2003-10-01	500
2004-01-01	-191
2004-04-01	45
2004-10-01	170
2005-01-01	-12
2005-04-01	-3
2005-07-01	-33
2006-04-01	130
2007-10-01	560
2009-07-01	2000
2010-07-01	550
2010-10-01	-600
2011-01-01	1075
2011-10-01	0
2012-04-01	800
2012-07-01	750
2013-01-01	299
2013-07-01	2500
2013-10-01	139
2014-04-01	2500
2014-07-01	1703
2014-10-01	-170
2015-01-01	500
2015-04-01	1500
2016-01-01	-173
2016-04-01	330
2016-07-01	260
2017-01-01	210
2017-04-01	-800
2017-10-01	764
2018-01-01	1
2018-04-01	-350