Quarter	Millions of US Dollars
2000-01-01	-1364
2000-04-01	-921
2000-07-01	1502
2000-10-01	12277
2001-01-01	-4179
2001-04-01	1342
2001-07-01	3924
2001-10-01	24585
2002-01-01	-19697
2002-04-01	3704
2002-07-01	10472
2002-10-01	32879
2003-01-01	-10341
2003-04-01	28
2003-07-01	323
2003-10-01	34367
2004-01-01	-28549
2004-04-01	3978
2004-07-01	-384
2004-10-01	73750
2005-01-01	-40675
2005-04-01	5690
2005-07-01	8199
2005-10-01	67503
2006-01-01	-77302
2006-04-01	4484
2006-07-01	11244
2006-10-01	80817
2007-01-01	-73559
2007-04-01	1809
2007-07-01	27221
2007-10-01	99916
2008-01-01	-38326
2008-04-01	-54474
2008-07-01	11415
2008-10-01	101921
2009-01-01	-67455
2009-04-01	21651
2009-07-01	19371
2009-10-01	112361
2010-01-01	-104640
2010-04-01	5479
2010-07-01	22148
2010-10-01	86723
2011-01-01	-102732
2011-04-01	-25624
2011-07-01	32431
2011-10-01	82485
2012-01-01	-54608
2012-04-01	-18930
2012-07-01	28576
2012-10-01	56605
2013-01-01	-53691
2013-04-01	-37074
2013-07-01	31069
2013-10-01	27534
2014-01-01	-21590
2014-04-01	-44122
2014-07-01	35881
2014-10-01	32170
2015-01-01	-5127
2015-04-01	-25450
2015-07-01	-5967
2015-10-01	14653
2016-01-01	-15448
2016-04-01	210
2016-07-01	17559
2016-10-01	9036
2017-01-01	-6038
2017-04-01	-8840
2017-07-01	10627
2017-10-01	20637
2018-01-01	-6103