Quarter	Millions of US Dollars
1971-01-01	25
1972-10-01	30
1973-01-01	52
1973-04-01	20
1973-07-01	72
1974-01-01	23
1974-04-01	59
1974-07-01	16
1974-10-01	36
1975-04-01	34
1975-10-01	38
1976-07-01	20
1977-01-01	30
1977-07-01	57
1978-04-01	83
1979-04-01	39
1979-07-01	13
1979-10-01	67
1980-01-01	116
1980-07-01	12
1980-10-01	95
1981-01-01	100
1981-04-01	100
1981-07-01	-72
1981-10-01	342
1982-01-01	300
1982-04-01	103
1982-07-01	164
1982-10-01	50
1983-01-01	242
1983-04-01	90
1983-07-01	34
1983-10-01	650
1984-01-01	37
1984-04-01	59
1984-07-01	349
1984-10-01	258
1985-01-01	398
1985-04-01	200
1985-07-01	242
1985-10-01	396
1986-01-01	197
1986-04-01	529
1986-07-01	1008
1986-10-01	-3
1987-01-01	-202
1987-04-01	189
1987-07-01	-99
1987-10-01	-345
1988-01-01	233
1988-04-01	200
1988-07-01	-257
1988-10-01	-90
1989-01-01	-268
1989-04-01	250
1989-07-01	1475
1989-10-01	16
1990-01-01	514
1990-04-01	249
1990-07-01	15
1990-10-01	188
1991-01-01	67
1991-04-01	769
1991-07-01	232
1991-10-01	-14
1992-01-01	354
1992-04-01	-261
1992-07-01	452
1992-10-01	973
1993-01-01	1683
1993-04-01	-324
1993-07-01	46
1993-10-01	-7
1994-01-01	-676
1994-04-01	416
1994-07-01	-71
1994-10-01	-191
1995-01-01	936
1995-04-01	527
1995-07-01	708
1995-10-01	2574
1996-01-01	1860
1996-04-01	1161
1996-07-01	1801
1996-10-01	3185
1997-01-01	5406
1997-04-01	3508
1997-07-01	3183
1997-10-01	2574
1998-01-01	2140
1998-04-01	2962
1998-07-01	4315
1998-10-01	-963
1999-01-01	5039
1999-04-01	2245
1999-07-01	2563
1999-10-01	6138
2000-01-01	2878
2000-04-01	4225
2000-07-01	841
2000-10-01	3125
2001-01-01	8596
2001-04-01	6641
2001-07-01	-2106
2001-10-01	7530
2002-01-01	4319
2002-04-01	2162
2002-07-01	756
2002-10-01	6527
2003-01-01	12673
2003-04-01	15348
2003-07-01	10551
2003-10-01	31444
2004-01-01	26296
2004-04-01	20511
2004-07-01	30215
2004-10-01	41595
2005-01-01	34907
2005-04-01	48543
2005-07-01	17290
2005-10-01	50738
2006-01-01	41516
2006-04-01	59795
2006-07-01	80679
2006-10-01	83920
2007-01-01	72348
2007-04-01	91367
2007-07-01	64869
2007-10-01	27011
2008-01-01	41432
2008-04-01	43323
2008-07-01	17252
2008-10-01	52656
2009-01-01	24062
2009-04-01	24357
2009-07-01	41616
2009-10-01	-16233
2010-01-01	11044
2010-04-01	-8370
2010-07-01	-31539
2010-10-01	-7793
2011-01-01	-70684
2011-04-01	-15436
2011-07-01	-30783
2011-10-01	-1632
2012-01-01	23241
2012-04-01	-12130
2012-07-01	-30364
2012-10-01	7894
2013-01-01	-640
2013-04-01	-22487
2013-07-01	-19494
2013-10-01	1142
2014-01-01	-35114
2014-04-01	-4752
2014-07-01	-16799
2014-10-01	-43203
2015-01-01	-27403
2015-04-01	28174
2015-07-01	-8947
2015-10-01	14017
2016-01-01	-6237
2016-04-01	-1174
2016-07-01	2200
2016-10-01	-7041
2017-01-01	1301
2017-04-01	-2478
2017-07-01	14355
2017-10-01	7629
2018-01-01	-5317
2018-04-01	9047