Quarter	Millions of US Dollars
2004-01-01	500
2006-04-01	251
2006-07-01	500
2006-10-01	3445
2007-04-01	1250
2007-07-01	3825
2007-10-01	2782
2008-01-01	1652
2008-04-01	463
2008-07-01	1866
2009-07-01	4459
2009-10-01	414
2010-04-01	1000
2010-10-01	2500
2011-01-01	-500
2011-04-01	335
2011-10-01	1502
2012-01-01	1915
2012-04-01	-1100
2012-10-01	-525
2013-01-01	1450
2013-07-01	-675
2013-10-01	-523
2014-01-01	300
2014-04-01	6649
2014-07-01	-2469
2014-10-01	1348
2015-01-01	49
2015-04-01	895
2015-07-01	51
2015-10-01	65
2016-01-01	452
2016-04-01	762
2016-07-01	7
2016-10-01	-470
2017-01-01	-456
2017-04-01	501
2017-07-01	-45
2017-10-01	2431
2018-01-01	-831
2018-04-01	1489