Quarter	Millions of US Dollars
2000-01-01	-1243
2000-04-01	-1750
2000-07-01	2448
2000-10-01	9405
2001-01-01	-4797
2001-04-01	1583
2001-07-01	7654
2001-10-01	20256
2002-01-01	-20845
2002-04-01	6829
2002-07-01	16249
2002-10-01	30569
2003-01-01	-4732
2003-04-01	1840
2003-07-01	-577
2003-10-01	25529
2004-01-01	-21031
2004-04-01	4543
2004-07-01	3690
2004-10-01	77137
2005-01-01	-50962
2005-04-01	8907
2005-07-01	-331
2005-10-01	62759
2006-01-01	-85167
2006-04-01	-964
2006-07-01	13431
2006-10-01	79521
2007-01-01	-80420
2007-04-01	-6042
2007-07-01	26773
2007-10-01	101734
2008-01-01	-42413
2008-04-01	-61966
2008-07-01	14310
2008-10-01	118003
2009-01-01	-74541
2009-04-01	23078
2009-07-01	26962
2009-10-01	109494
2010-01-01	-95533
2010-04-01	17900
2010-07-01	26653
2010-10-01	77268
2011-01-01	-102360
2011-04-01	-19079
2011-07-01	49245
2011-10-01	83028
2012-01-01	-58372
2012-04-01	-9565
2012-07-01	32772
2012-10-01	53243
2013-01-01	-54734
2013-04-01	-39492
2013-07-01	31826
2013-10-01	19708
2014-01-01	-14475
2014-04-01	-40508
2014-07-01	44279
2014-10-01	30244
2015-01-01	-693
2015-04-01	-36739
2015-07-01	-4988
2015-10-01	9622
2016-01-01	-7740
2016-04-01	8065
2016-07-01	19691
2016-10-01	-5568
2017-01-01	-5461
2017-04-01	-6270
2017-07-01	15083
2017-10-01	10067
2018-01-01	-3908