Quarter	Millions of US Dollars
1971-01-01	10
1972-04-01	26
1973-01-01	23
1973-04-01	91
1974-01-01	5
1975-07-01	38
1975-10-01	19
1976-04-01	-8
1976-07-01	75
1976-10-01	115
1977-01-01	20
1977-04-01	-8
1977-07-01	58
1977-10-01	29
1978-07-01	17
1979-01-01	29
1979-07-01	932
1979-10-01	507
1980-04-01	9
1980-10-01	80
1981-01-01	78
1981-04-01	4
1981-07-01	-27
1981-10-01	38
1982-01-01	53
1982-04-01	50
1982-07-01	38
1983-01-01	191
1983-04-01	150
1983-07-01	60
1983-10-01	339
1984-01-01	124
1984-04-01	88
1984-07-01	443
1984-10-01	463
1985-01-01	428
1985-04-01	294
1985-07-01	599
1985-10-01	168
1986-01-01	1118
1986-04-01	712
1986-07-01	748
1986-10-01	526
1987-01-01	165
1987-04-01	62
1987-07-01	275
1987-10-01	-158
1988-01-01	96
1988-04-01	88
1988-07-01	88
1988-10-01	494
1989-01-01	-118
1989-04-01	46
1989-07-01	163
1989-10-01	43
1990-01-01	296
1990-04-01	1183
1990-07-01	-187
1990-10-01	201
1991-01-01	1021
1991-04-01	99
1991-07-01	-91
1991-10-01	400
1992-01-01	-52
1992-04-01	-62
1992-07-01	-357
1992-10-01	530
1993-01-01	-7
1993-04-01	431
1993-07-01	151
1993-10-01	593
1994-01-01	300
1994-04-01	246
1994-07-01	701
1994-10-01	1324
1995-01-01	1271
1995-04-01	985
1995-07-01	898
1995-10-01	-291
1996-01-01	-1117
1996-04-01	-76
1996-07-01	-1703
1996-10-01	-1427
1997-01-01	-178
1997-04-01	418
1997-07-01	1407
1997-10-01	556
1998-01-01	-458
1998-04-01	-1443
1998-07-01	-317
1998-10-01	-163
1999-01-01	-341
1999-04-01	-317
1999-07-01	393
1999-10-01	-1636
2000-01-01	200
2000-04-01	1123
2000-07-01	3658
2000-10-01	-2470
2001-01-01	8137
2001-04-01	3507
2001-07-01	-156
2001-10-01	-600
2002-01-01	3551
2002-04-01	-559
2002-07-01	-376
2002-10-01	595
2003-01-01	861
2003-04-01	656
2003-07-01	57
2003-10-01	320
2004-01-01	922
2004-04-01	1004
2004-07-01	2304
2004-10-01	-799
2005-01-01	460
2005-04-01	604
2005-07-01	-436
2005-10-01	583
2006-01-01	4976
2006-04-01	839
2006-07-01	-5135
2006-10-01	6373
2007-01-01	5495
2007-04-01	15035
2007-07-01	-1111
2007-10-01	4058
2008-01-01	-4506
2008-04-01	16296
2008-07-01	-2217
2008-10-01	21290
2009-01-01	9291
2009-04-01	18735
2009-07-01	1046
2009-10-01	7031
2010-01-01	6629
2010-04-01	3125
2010-07-01	8362
2010-10-01	-2887
2011-01-01	1260
2011-04-01	540
2011-07-01	-7696
2011-10-01	-818
2012-01-01	-7807
2012-04-01	3047
2012-07-01	2348
2012-10-01	258
2013-01-01	865
2013-04-01	2928
2013-07-01	8859
2013-10-01	3501
2014-01-01	-3857
2014-04-01	-821
2014-07-01	-163
2014-10-01	1549
2015-01-01	2334
2015-04-01	2478
2015-07-01	-640
2015-10-01	3874
2016-01-01	7726
2016-04-01	-265
2016-07-01	3607
2016-10-01	-322
2017-01-01	-2283
2017-04-01	1809
2017-07-01	1042
2017-10-01	-433
2018-01-01	-134
2018-04-01	-1211