Quarter	Millions of US Dollars
1999-04-01	114
1999-07-01	12
1999-10-01	47
2000-01-01	-22
2000-04-01	-34
2000-07-01	-19
2000-10-01	-43
2001-01-01	2
2001-04-01	223
2001-07-01	391
2001-10-01	114
2002-01-01	242
2002-04-01	-82
2002-07-01	-56
2002-10-01	-31
2003-01-01	231
2003-04-01	66
2003-07-01	166
2003-10-01	1
2004-01-01	514
2004-04-01	373
2004-07-01	195
2004-10-01	103
2005-01-01	1464
2005-04-01	1242
2005-07-01	1470
2005-10-01	841
2006-01-01	360
2006-04-01	352
2006-07-01	126
2006-10-01	523
2007-01-01	472
2007-04-01	2099
2007-07-01	442
2007-10-01	1199
2008-01-01	1480
2008-04-01	608
2008-07-01	-498
2008-10-01	-1516
2009-01-01	752
2009-04-01	1344
2009-07-01	2217
2009-10-01	492
2010-01-01	823
2010-04-01	435
2010-07-01	1776
2010-10-01	-115
2011-01-01	-181
2011-04-01	342
2011-07-01	1007
2011-10-01	1102
2012-01-01	533
2012-04-01	908
2012-07-01	691
2012-10-01	135
2013-01-01	126
2013-04-01	55
2013-07-01	-332
2013-10-01	-297
2014-01-01	-790
2014-04-01	-311
2014-07-01	1529
2014-10-01	-621
2015-01-01	-604
2015-04-01	230
2015-07-01	852
2015-10-01	-325
2016-01-01	2080
2016-04-01	-954
2016-07-01	403
2016-10-01	-927
2017-01-01	-715
2017-04-01	154
2017-07-01	-1847
2017-10-01	631
2018-01-01	-373