Quarter	Millions of US Dollars
1987-07-01	307
1987-10-01	1978
1988-01-01	-12
1988-04-01	-84
1988-07-01	-133
1988-10-01	-59
1989-01-01	-791
1989-04-01	683
1989-07-01	363
1989-10-01	1929
1990-01-01	-1604
1990-04-01	2208
1990-07-01	4487
1990-10-01	788
1991-01-01	-377
1991-04-01	-775
1991-07-01	1765
1991-10-01	-169
1992-01-01	1071
1992-04-01	-2212
1992-07-01	1513
1992-10-01	1656
1993-01-01	1354
1993-04-01	3969
1993-07-01	5708
1993-10-01	-1689
1994-01-01	2578
1994-04-01	2503
1994-07-01	-6731
1994-10-01	4914
1995-01-01	2687
1995-04-01	3455
1995-07-01	-7213
1995-10-01	9190
1996-01-01	2277
1996-04-01	10477
1996-07-01	4393
1996-10-01	4671
1997-01-01	3543
1997-04-01	-1500
1997-07-01	-3598
1997-10-01	5633
1998-01-01	7457
1998-04-01	3624
1998-07-01	7275
1998-10-01	-1666
1999-01-01	-648
1999-04-01	-1989
1999-07-01	-2674
1999-10-01	-1761
2000-01-01	4597
2000-04-01	-2289
2000-07-01	-1251
2000-10-01	-4575
2001-01-01	2072
2001-04-01	-2104
2001-07-01	244
2001-10-01	-1670
2002-01-01	2805
2002-04-01	-2687
2002-07-01	-1154
2002-10-01	-50
2003-01-01	901
2003-04-01	1009
2003-07-01	1761
2003-10-01	-540
2004-01-01	2619
2004-04-01	-807
2004-07-01	-680
2004-10-01	-940
2005-01-01	-379
2005-04-01	-1193
2005-07-01	448
2005-10-01	-530
2006-01-01	179
2006-04-01	-2898
2006-07-01	-1314
2006-10-01	1905
2007-01-01	-1219
2007-04-01	-2841
2007-07-01	1445
2007-10-01	-397
2008-01-01	-17
2008-04-01	-747
2008-07-01	357
2008-10-01	2065
2009-01-01	23
2009-04-01	-2494
2009-07-01	-313
2009-10-01	1564
2010-01-01	3997
2010-04-01	-1548
2010-07-01	867
2010-10-01	-102
2011-01-01	2859
2011-04-01	-689
2011-07-01	2950
2011-10-01	1430
2012-01-01	6142
2012-04-01	5001
2012-07-01	5703
2012-10-01	2000
2013-01-01	7353
2013-04-01	1704
2013-07-01	3437
2013-10-01	1631
2014-01-01	4726
2014-04-01	1519
2014-07-01	2418
2014-10-01	-241
2015-01-01	3967
2015-04-01	-486
2015-07-01	-381
2015-10-01	-2012
2016-01-01	1761
2016-04-01	801
2016-07-01	699
2016-10-01	-2362
2017-01-01	6395
2017-04-01	900
2017-07-01	1506
2017-10-01	73
2018-01-01	3058