Quarter	Millions of US Dollars
2002-04-01	17768
2002-07-01	20664
2002-10-01	-693
2003-01-01	17410
2003-04-01	11758
2003-07-01	19059
2003-10-01	-3839
2004-01-01	15032
2004-04-01	4421
2004-07-01	6994
2004-10-01	16834
2005-01-01	21168
2005-04-01	17763
2005-07-01	15856
2005-10-01	8366
2006-01-01	28700
2006-04-01	-4388
2006-07-01	20376
2006-10-01	18991
2007-01-01	28332
2007-04-01	32896
2007-07-01	4022
2007-10-01	36797
2008-01-01	16733
2008-04-01	36295
2008-07-01	-20759
2008-10-01	54956
2009-01-01	-3991
2009-04-01	36850
2009-07-01	53159
2009-10-01	68917
2010-01-01	16497
2010-04-01	72507
2010-07-01	13628
2010-10-01	52925
2011-01-01	6614
2011-04-01	80082
2011-07-01	2156
2011-10-01	47018
2012-01-01	26672
2012-04-01	76082
2012-07-01	-27986
2012-10-01	68714
2013-01-01	-25610
2013-04-01	19187
2013-07-01	6034
2013-10-01	67024
2014-01-01	-7697
2014-04-01	65075
2014-07-01	-16556
2014-10-01	86662
2015-01-01	43194
2015-04-01	46574
2015-07-01	54213
2015-10-01	33839
2016-01-01	29358
2016-04-01	35424
2016-07-01	31274
2016-10-01	76941
2017-01-01	68771
2017-04-01	32989
2017-07-01	39853
2017-10-01	40014
2018-01-01	40790