Quarter	Millions of US Dollars
1975-07-01	19
1976-01-01	28
1977-07-01	22
1980-07-01	10
1982-07-01	-15
1983-01-01	-8
1984-07-01	25
1985-07-01	-18
1985-10-01	38
1986-01-01	234
1986-10-01	150
1987-04-01	71
1987-07-01	-17
1989-01-01	40
1989-04-01	-26
1990-04-01	-77
1990-07-01	301
1990-10-01	-150
1991-07-01	-25
1992-07-01	200
1993-04-01	-200
1993-07-01	110
1994-04-01	123
1994-07-01	-123
1994-10-01	1086
1995-01-01	-4
1995-04-01	11
1995-07-01	8
1995-10-01	-388
1996-01-01	211
1996-04-01	349
1996-07-01	142
1996-10-01	190
1997-01-01	801
1997-04-01	603
1997-07-01	275
1997-10-01	546
1998-01-01	756
1998-04-01	29
1998-07-01	1277
1998-10-01	769
1999-01-01	1335
1999-04-01	153
1999-07-01	1514
1999-10-01	-1653
2000-01-01	-876
2000-04-01	534
2000-07-01	967
2000-10-01	1995
2001-01-01	827
2001-04-01	-532
2001-07-01	-2885
2001-10-01	-598
2002-01-01	-192
2002-04-01	-15
2002-07-01	-165
2002-10-01	-279
2003-01-01	-166
2003-04-01	-54
2003-07-01	-71
2003-10-01	-113
2004-01-01	50
2004-04-01	1056
2004-07-01	63
2004-10-01	-142
2005-01-01	-251
2005-04-01	-135
2005-07-01	284
2005-10-01	1574
2006-01-01	229
2006-04-01	1430
2006-07-01	679
2006-10-01	-26
2007-01-01	698
2007-04-01	1766
2007-07-01	-647
2007-10-01	696
2008-01-01	-552
2008-04-01	2517
2008-07-01	-93
2008-10-01	-741
2009-01-01	-1088
2009-04-01	638
2009-07-01	347
2009-10-01	728
2010-01-01	233
2010-04-01	596
2010-07-01	-114
2010-10-01	1246
2011-01-01	406
2011-04-01	-1075
2011-07-01	899
2011-10-01	1254
2012-01-01	1936
2012-04-01	1283
2012-07-01	763
2012-10-01	405
2013-01-01	2067
2013-04-01	-2459
2013-07-01	4738
2013-10-01	5683
2014-01-01	-437
2014-04-01	8576
2014-07-01	3298
2014-10-01	5683
2015-01-01	-689
2015-04-01	3255
2015-07-01	3386
2015-10-01	-710
2016-01-01	-1391
2016-04-01	1158
2016-07-01	536
2016-10-01	500
2017-01-01	14059
2017-04-01	-582
2017-07-01	8372
2017-10-01	-3062
2018-01-01	2705
2018-04-01	4715