Quarter	Millions of US Dollars
1972-07-01	20
1975-04-01	2
1982-07-01	-20
1986-07-01	105
1987-04-01	-2
1996-07-01	-105
1996-10-01	600
1997-04-01	75
1997-07-01	200
1997-10-01	425
1998-04-01	74
1998-07-01	385
1999-01-01	500
1999-10-01	600
2000-01-01	350
2000-04-01	125
2000-07-01	446
2000-10-01	100
2001-04-01	600
2002-07-01	-100
2003-01-01	50
2003-04-01	30
2004-01-01	270
2004-04-01	-75
2004-07-01	-85
2004-10-01	125
2005-01-01	-350
2005-04-01	-125
2005-07-01	-275
2006-01-01	1392
2006-04-01	55
2006-10-01	-350
2007-01-01	-99
2007-07-01	-412
2007-10-01	-225
2008-01-01	250
2008-04-01	2000
2009-01-01	0
2009-04-01	0
2009-10-01	-600
2010-04-01	500
2010-07-01	-175
2010-10-01	105
2011-01-01	-145
2011-04-01	-600
2011-07-01	0
2011-10-01	5000
2012-01-01	581
2012-10-01	2500
2013-01-01	-1000
2013-04-01	-1680
2013-07-01	300
2013-10-01	-2100
2014-07-01	0
2014-10-01	3300
2015-01-01	113
2015-10-01	3712
2016-01-01	-77
2016-07-01	289
2016-10-01	-979
2017-01-01	-206
2017-04-01	68
2017-07-01	-26
2018-01-01	750
2018-04-01	-365