Quarter	Millions of US Dollars
1971-01-01	86
1971-04-01	51
1971-07-01	24
1971-10-01	81
1972-01-01	253
1972-04-01	154
1972-07-01	219
1972-10-01	416
1973-01-01	161
1973-04-01	392
1973-07-01	130
1973-10-01	544
1974-01-01	130
1974-04-01	493
1974-07-01	67
1974-10-01	166
1975-01-01	355
1975-04-01	553
1975-07-01	187
1975-10-01	209
1976-01-01	204
1976-04-01	478
1976-07-01	626
1976-10-01	598
1977-01-01	694
1977-04-01	864
1977-07-01	1256
1977-10-01	1338
1978-01-01	1744
1978-04-01	1386
1978-07-01	864
1978-10-01	1150
1979-01-01	1020
1979-04-01	666
1979-07-01	850
1979-10-01	253
1980-01-01	-89
1980-04-01	648
1980-07-01	576
1980-10-01	219
1981-01-01	158
1981-04-01	646
1981-07-01	580
1981-10-01	963
1982-01-01	1037
1982-04-01	268
1982-07-01	-71
1982-10-01	467
1983-01-01	-305
1983-04-01	51
1983-07-01	1236
1983-10-01	-101
1984-01-01	320
1984-04-01	52
1984-07-01	203
1984-10-01	1352
1985-01-01	856
1985-04-01	2074
1985-07-01	639
1985-10-01	-164
1986-01-01	1047
1986-04-01	361
1986-07-01	170
1986-10-01	-523
1987-01-01	-28
1987-04-01	-292
1987-07-01	-145
1987-10-01	-202
1988-01-01	356
1988-04-01	-609
1988-07-01	525
1988-10-01	826
1989-01-01	447
1989-04-01	-145
1989-07-01	1865
1989-10-01	717
1990-01-01	36046
1990-04-01	512
1990-07-01	1187
1990-10-01	16714
1991-01-01	2129
1991-04-01	3975
1991-07-01	1191
1991-10-01	4725
1992-01-01	5060
1992-04-01	2637
1992-07-01	3676
1992-10-01	6148
1993-01-01	3368
1993-04-01	23928
1993-07-01	11946
1993-10-01	24146
1994-01-01	13052
1994-04-01	46617
1994-07-01	12767
1994-10-01	11343
1995-01-01	413
1995-04-01	5122
1995-07-01	14657
1995-10-01	9297
1996-01-01	12800
1996-04-01	16932
1996-07-01	19370
1996-10-01	24555
1997-01-01	24066
1997-04-01	28927
1997-07-01	24304
1997-10-01	1629
1998-01-01	13206
1998-04-01	23611
1998-07-01	3576
1998-10-01	-25758
1999-01-01	1558
1999-04-01	16509
1999-07-01	192
1999-10-01	10654
2000-01-01	20442
2000-04-01	3755
2000-07-01	35199
2000-10-01	-5205
2001-01-01	9520
2001-04-01	-2043
2001-07-01	-1891
2001-10-01	-677
2002-01-01	5770
2002-04-01	2790
2002-07-01	2520
2002-10-01	3278
2003-01-01	2249
2003-04-01	4702
2003-07-01	8009
2003-10-01	7145
2004-01-01	16700
2004-04-01	8642
2004-07-01	6597
2004-10-01	15784
2005-01-01	21608
2005-04-01	-8898
2005-07-01	7674
2005-10-01	20527
2006-01-01	32528
2006-04-01	-8122
2006-07-01	21265
2006-10-01	36983
2007-01-01	24517
2007-04-01	41019
2007-07-01	5975
2007-10-01	16651
2008-01-01	-1946
2008-04-01	23963
2008-07-01	3629
2008-10-01	-27779
2009-01-01	5102
2009-04-01	20865
2009-07-01	36266
2009-10-01	40479
2010-01-01	23796
2010-04-01	29215
2010-07-01	37519
2010-10-01	36956
2011-01-01	47224
2011-04-01	36731
2011-07-01	17697
2011-10-01	36542
2012-01-01	44406
2012-04-01	45588
2012-07-01	62646
2012-10-01	69752
2013-01-01	36066
2013-04-01	50116
2013-07-01	52054
2013-10-01	72932
2014-01-01	20993
2014-04-01	58075
2014-07-01	39779
2014-10-01	70932
2015-01-01	34141
2015-04-01	49997
2015-07-01	13134
2015-10-01	-3013
2016-01-01	34151
2016-04-01	77290
2016-07-01	30126
2016-10-01	87494
2017-01-01	69078
2017-04-01	65545
2017-07-01	69263
2017-10-01	87599
2018-01-01	73162
2018-04-01	47323