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	-355
1988-10-01	-90
1989-01-01	-68
1989-04-01	250
1989-07-01	1772
1989-10-01	-54
1990-01-01	278
1990-04-01	249
1990-07-01	-238
1990-10-01	37
1991-01-01	28
1991-04-01	558
1991-07-01	5
1991-10-01	-56
1992-01-01	174
1992-04-01	-261
1992-07-01	372
1992-10-01	973
1993-01-01	1596
1993-04-01	-139
1993-07-01	100
1993-10-01	-109
1994-01-01	-636
1994-04-01	327
1994-07-01	-299
1994-10-01	-553
1995-01-01	533
1995-04-01	330
1995-07-01	282
1995-10-01	964
1996-01-01	3174
1996-04-01	-70
1996-07-01	476
1996-10-01	849
1997-01-01	677
1997-04-01	193
1997-07-01	562
1997-10-01	-431
1998-01-01	1177
1998-04-01	433
1998-07-01	1193
1998-10-01	-505
1999-01-01	1869
1999-04-01	542
1999-07-01	743
1999-10-01	2163
2000-01-01	2510
2000-04-01	3374
2000-07-01	-1548
2000-10-01	-175
2001-01-01	6033
2001-04-01	229
2001-07-01	2286
2001-10-01	3217
2002-01-01	1703
2002-04-01	-800
2002-07-01	1923
2002-10-01	4950
2003-01-01	2583
2003-04-01	5279
2003-07-01	4811
2003-10-01	3444
2004-01-01	8427
2004-04-01	2565
2004-07-01	11016
2004-10-01	8688
2005-01-01	10002
2005-04-01	13649
2005-07-01	10825
2005-10-01	14763
2006-01-01	8690
2006-04-01	15890
2006-07-01	25135
2006-10-01	18298
2007-01-01	42461
2007-04-01	30499
2007-07-01	44479
2007-10-01	-2120
2008-01-01	18932
2008-04-01	34125
2008-07-01	3055
2008-10-01	44684
2009-01-01	13107
2009-04-01	15852
2009-07-01	14238
2009-10-01	6451
2010-01-01	16386
2010-04-01	3006
2010-07-01	-45512
2010-10-01	10223
2011-01-01	-31011
2011-04-01	-10914
2011-07-01	-16186
2011-10-01	-2447
2012-01-01	26865
2012-04-01	6669
2012-07-01	-24869
2012-10-01	5386
2013-01-01	2523
2013-04-01	-15965
2013-07-01	-1405
2013-10-01	10731
2014-01-01	-33553
2014-04-01	-4973
2014-07-01	-3845
2014-10-01	-27749
2015-01-01	-25537
2015-04-01	13805
2015-07-01	-5240
2015-10-01	9649
2016-01-01	4398
2016-04-01	2001
2016-07-01	3438
2016-10-01	-364
2017-01-01	-2920
2017-04-01	1204
2017-07-01	-965
2017-10-01	-2198
2018-01-01	309
2018-04-01	739