Quarter	Millions of US Dollars
1988-07-01	-1219
1988-10-01	-1610
1989-01-01	-463
1989-04-01	-348
1989-07-01	319
1989-10-01	922
1990-01-01	271
1990-04-01	77
1990-07-01	929
1990-10-01	-257
1991-01-01	205
1991-04-01	-1034
1991-07-01	1025
1991-10-01	94
1992-01-01	131
1992-04-01	851
1992-07-01	58
1992-10-01	-534
1993-01-01	-176
1993-04-01	-721
1993-07-01	-2585
1993-10-01	-895
1994-01-01	-616
1994-04-01	-1121
1994-07-01	156
1994-10-01	870
1995-01-01	-885
1995-04-01	369
1995-07-01	-865
1995-10-01	531
1996-01-01	1548
1996-04-01	1321
1996-07-01	-207
1996-10-01	215
1997-01-01	-87
1997-04-01	285
1997-07-01	222
1997-10-01	1878
1998-01-01	469
1998-04-01	-648
1998-07-01	48
1998-10-01	-842
1999-01-01	2429
1999-04-01	726
1999-07-01	536
1999-10-01	425
2000-01-01	2955
2000-04-01	502
2000-07-01	241
2000-10-01	2790
2001-01-01	-276
2001-04-01	-118
2001-07-01	500
2001-10-01	1482
2002-01-01	579
2002-04-01	1576
2002-07-01	-515
2002-10-01	844
2003-01-01	1438
2003-04-01	1043
2003-07-01	-4230
2003-10-01	987
2004-01-01	279
2004-04-01	2243
2004-07-01	849
2004-10-01	-703
2005-01-01	1662
2005-04-01	-608
2005-07-01	-1183
2005-10-01	4248
2006-01-01	1676
2006-04-01	-257
2006-07-01	46
2006-10-01	1505
2007-01-01	96
2007-04-01	-47
2007-07-01	-4028
2007-10-01	-2672
2008-01-01	-609
2008-04-01	-2308
2008-07-01	-110
2008-10-01	-1927
2009-01-01	-243
2009-04-01	-655
2009-07-01	136
2009-10-01	-351
2010-01-01	-85
2010-04-01	-270
2010-07-01	856
2010-10-01	-1112
2011-01-01	1125
2011-04-01	-592
2011-07-01	-195
2011-10-01	-453
2012-01-01	3267
2012-04-01	1461
2012-07-01	686
2012-10-01	2373
2013-01-01	810
2013-04-01	-617
2013-07-01	1683
2013-10-01	1189
2014-01-01	920
2014-04-01	322
2014-07-01	-1188
2014-10-01	901
2015-01-01	1684
2015-04-01	136
2015-07-01	217
2015-10-01	-1601
2016-01-01	465
2016-04-01	-416
2016-07-01	-1217
2016-10-01	-1575
2017-01-01	107
2017-04-01	1482
2017-07-01	1922
2017-10-01	-531
2018-01-01	796