Quarter	Millions of US Dollars
1987-07-01	227
1987-10-01	1610
1988-01-01	1005
1988-04-01	2157
1988-07-01	1941
1988-10-01	5629
1989-01-01	-34
1989-04-01	7042
1989-07-01	260
1989-10-01	-2190
1990-01-01	2832
1990-04-01	547
1990-07-01	3684
1990-10-01	-5029
1991-01-01	1625
1991-04-01	4599
1991-07-01	4666
1991-10-01	-617
1992-01-01	3072
1992-04-01	9780
1992-07-01	-1875
1992-10-01	4208
1993-01-01	3471
1993-04-01	5942
1993-07-01	1913
1993-10-01	-1164
1994-01-01	2882
1994-04-01	-393
1994-07-01	-4562
1994-10-01	10662
1995-01-01	2370
1995-04-01	3086
1995-07-01	-6866
1995-10-01	13126
1996-01-01	931
1996-04-01	9229
1996-07-01	6598
1996-10-01	7425
1997-01-01	4903
1997-04-01	-3314
1997-07-01	-725
1997-10-01	12663
1998-01-01	6582
1998-04-01	3555
1998-07-01	9909
1998-10-01	-3435
1999-01-01	-474
1999-04-01	-5375
1999-07-01	-53
1999-10-01	3707
2000-01-01	5271
2000-04-01	-1104
2000-07-01	-821
2000-10-01	509
2001-01-01	5734
2001-04-01	-1646
2001-07-01	3423
2001-10-01	654
2002-01-01	7363
2002-04-01	1281
2002-07-01	3565
2002-10-01	3631
2003-01-01	4792
2003-04-01	2467
2003-07-01	4315
2003-10-01	5731
2004-01-01	7089
2004-04-01	2763
2004-07-01	3194
2004-10-01	4929
2005-01-01	1185
2005-04-01	3285
2005-07-01	15
2005-10-01	2373
2006-01-01	3584
2006-04-01	2092
2006-07-01	-1156
2006-10-01	2923
2007-01-01	-247
2007-04-01	-830
2007-07-01	-2391
2007-10-01	813
2008-01-01	5402
2008-04-01	4324
2008-07-01	-2055
2008-10-01	1354
2009-01-01	3384
2009-04-01	-7
2009-07-01	-3015
2009-10-01	6405
2010-01-01	7312
2010-04-01	2262
2010-07-01	147
2010-10-01	8446
2011-01-01	3131
2011-04-01	4803
2011-07-01	3560
2011-10-01	7588
2012-01-01	5296
2012-04-01	11437
2012-07-01	6909
2012-10-01	8332
2013-01-01	11350
2013-04-01	3527
2013-07-01	4425
2013-10-01	4983
2014-01-01	5663
2014-04-01	7950
2014-07-01	-1095
2014-10-01	7469
2015-01-01	4317
2015-04-01	1210
2015-07-01	-225
2015-10-01	130
2016-01-01	1853
2016-04-01	4165
2016-07-01	-3816
2016-10-01	-770
2017-01-01	10015
2017-04-01	900
2017-07-01	-256
2017-10-01	1568
2018-01-01	3716