Quarter	Millions of US Dollars
1977-01-01	42
1982-01-01	-43
2002-07-01	230
2004-01-01	1300
2004-10-01	1000
2005-01-01	1075
2005-04-01	2000
2005-07-01	508
2005-10-01	2359
2006-01-01	5382
2006-04-01	2706
2006-07-01	1974
2006-10-01	11522
2007-01-01	4405
2007-04-01	1707
2007-07-01	4242
2007-10-01	3514
2008-01-01	226
2008-04-01	5237
2008-07-01	2513
2008-10-01	-3758
2009-01-01	-1766
2009-04-01	5786
2009-07-01	5878
2009-10-01	-4339
2010-01-01	-1246
2010-04-01	-1417
2010-07-01	220
2010-10-01	2176
2011-01-01	143
2011-04-01	1682
2011-07-01	-53
2011-10-01	1722
2012-01-01	1328
2012-04-01	-923
2012-07-01	914
2012-10-01	5640
2013-01-01	3319
2013-04-01	2112
2013-07-01	-654
2013-10-01	1611
2014-01-01	1357
2014-04-01	6588
2014-07-01	-800
2014-10-01	4669
2015-01-01	3948
2015-04-01	5174
2015-07-01	2064
2015-10-01	661
2016-01-01	446
2016-04-01	10816
2016-07-01	3372
2016-10-01	3257
2017-01-01	2434
2017-04-01	3465
2017-07-01	2462
2017-10-01	13034
2018-01-01	2784
2018-04-01	2379