Quarter	Millions of US Dollars
1987-07-01	-201
1987-10-01	1566
1988-01-01	623
1988-04-01	1484
1988-07-01	753
1988-10-01	3687
1989-01-01	1105
1989-04-01	-2185
1989-07-01	-830
1989-10-01	-2990
1990-01-01	-1667
1990-04-01	-85
1990-07-01	-206
1990-10-01	71
1991-01-01	3017
1991-04-01	1605
1991-07-01	4947
1991-10-01	-19
1992-01-01	3465
1992-04-01	9218
1992-07-01	-6406
1992-10-01	532
1993-01-01	1607
1993-04-01	-437
1993-07-01	1234
1993-10-01	2149
1994-01-01	1502
1994-04-01	-1530
1994-07-01	-606
1994-10-01	2962
1995-01-01	529
1995-04-01	-1466
1995-07-01	1081
1995-10-01	1987
1996-01-01	339
1996-04-01	-882
1996-07-01	3086
1996-10-01	2521
1997-01-01	1047
1997-04-01	-1085
1997-07-01	-601
1997-10-01	1893
1998-01-01	467
1998-04-01	-794
1998-07-01	997
1998-10-01	662
1999-01-01	2151
1999-04-01	3
1999-07-01	3639
1999-10-01	3484
2000-01-01	2627
2000-04-01	-108
2000-07-01	-138
2000-10-01	1742
2001-01-01	4158
2001-04-01	806
2001-07-01	3345
2001-10-01	2938
2002-01-01	4160
2002-04-01	3192
2002-07-01	4262
2002-10-01	2437
2003-01-01	4445
2003-04-01	226
2003-07-01	1025
2003-10-01	1679
2004-01-01	3179
2004-04-01	1317
2004-07-01	3026
2004-10-01	2602
2005-01-01	2605
2005-04-01	1705
2005-07-01	295
2005-10-01	1762
2006-01-01	1393
2006-04-01	2929
2006-07-01	2367
2006-10-01	127
2007-01-01	1131
2007-04-01	2275
2007-07-01	-1394
2007-10-01	2211
2008-01-01	5423
2008-04-01	3677
2008-07-01	-1954
2008-10-01	2488
2009-01-01	6569
2009-04-01	2482
2009-07-01	-1911
2009-10-01	3135
2010-01-01	3772
2010-04-01	2190
2010-07-01	639
2010-10-01	6096
2011-01-01	-35
2011-04-01	3779
2011-07-01	-660
2011-10-01	5367
2012-01-01	-168
2012-04-01	4520
2012-07-01	1024
2012-10-01	4996
2013-01-01	4180
2013-04-01	1397
2013-07-01	1618
2013-10-01	2676
2014-01-01	1328
2014-04-01	3336
2014-07-01	-3088
2014-10-01	3160
2015-01-01	-32
2015-04-01	1702
2015-07-01	-1825
2015-10-01	2969
2016-01-01	848
2016-04-01	932
2016-07-01	-3265
2016-10-01	2498
2017-01-01	1727
2017-04-01	-953
2017-07-01	-2966
2017-10-01	1096
2018-01-01	-340