Quarter	Millions of US Dollars
1978-07-01	62
1983-07-01	-25
1984-07-01	90
1986-07-01	-34
1987-07-01	-40
1992-07-01	-50
2002-01-01	450
2002-07-01	300
2003-10-01	200
2004-10-01	500
2005-01-01	-450
2005-04-01	500
2005-07-01	697
2005-10-01	68
2006-01-01	535
2006-04-01	279
2006-07-01	-555
2006-10-01	579
2007-01-01	-9
2007-04-01	412
2007-07-01	81
2007-10-01	-105
2008-01-01	359
2008-04-01	-39
2008-07-01	-9
2008-10-01	-564
2009-01-01	-23
2009-10-01	0
2010-04-01	-500
2010-07-01	1000
2011-01-01	177
2011-04-01	-926
2011-07-01	250
2011-10-01	250
2012-04-01	92
2012-07-01	-806
2012-10-01	764
2013-01-01	-195
2013-07-01	-68
2014-01-01	500
2014-04-01	1000
2014-07-01	717
2015-01-01	82
2015-04-01	917
2015-07-01	79
2015-10-01	-703
2016-01-01	816
2016-04-01	582
2016-07-01	315
2016-10-01	3252
2017-01-01	6240
2017-04-01	2717
2017-07-01	33
2017-10-01	-267
2018-01-01	103
2018-04-01	171