Quarter	Millions of US Dollars
1971-10-01	31
1972-01-01	82
1972-04-01	40
1972-07-01	51
1972-10-01	145
1973-01-01	95
1973-04-01	25
1973-07-01	76
1973-10-01	109
1974-01-01	5
1974-07-01	2
1974-10-01	75
1975-01-01	130
1975-04-01	147
1975-07-01	49
1975-10-01	62
1976-01-01	62
1976-04-01	193
1976-07-01	131
1976-10-01	272
1977-01-01	319
1977-04-01	612
1977-07-01	877
1977-10-01	1088
1978-01-01	1176
1978-04-01	685
1978-07-01	396
1978-10-01	610
1979-01-01	574
1979-04-01	264
1979-07-01	483
1979-10-01	281
1980-01-01	-47
1980-04-01	551
1980-07-01	288
1980-10-01	262
1981-01-01	170
1981-04-01	781
1981-07-01	480
1981-10-01	870
1982-01-01	613
1982-04-01	-178
1982-07-01	-9
1982-10-01	-93
1983-01-01	-432
1983-04-01	-153
1983-07-01	-42
1983-10-01	-235
1984-01-01	-144
1984-04-01	-153
1984-07-01	-339
1984-10-01	-122
1985-01-01	-24
1985-04-01	-49
1985-07-01	-73
1985-10-01	-1013
1986-01-01	-81
1986-04-01	-376
1986-07-01	-157
1986-10-01	-591
1987-01-01	-512
1987-04-01	-238
1987-07-01	-328
1987-10-01	-556
1988-01-01	-141
1988-04-01	-858
1988-07-01	-828
1988-10-01	-235
1989-01-01	-139
1989-04-01	-90
1989-07-01	728
1989-10-01	-417
1990-01-01	35315
1990-04-01	767
1990-07-01	284
1990-10-01	16385
1991-01-01	1507
1991-04-01	1117
1991-07-01	1052
1991-10-01	2334
1992-01-01	1104
1992-04-01	2121
1992-07-01	1006
1992-10-01	2156
1993-01-01	1101
1993-04-01	21567
1993-07-01	8975
1993-10-01	16184
1994-01-01	7311
1994-04-01	44633
1994-07-01	3009
1994-10-01	2408
1995-01-01	-37
1995-04-01	3704
1995-07-01	6541
1995-10-01	4898
1996-01-01	9018
1996-04-01	11735
1996-07-01	7243
1996-10-01	7711
1997-01-01	14463
1997-04-01	13414
1997-07-01	12393
1997-10-01	-1672
1998-01-01	9444
1998-04-01	13461
1998-07-01	424
1998-10-01	-23072
1999-01-01	1198
1999-04-01	13913
1999-07-01	5095
1999-10-01	8781
2000-01-01	15725
2000-04-01	-2545
2000-07-01	16488
2000-10-01	-3440
2001-01-01	11477
2001-04-01	-4188
2001-07-01	-100
2001-10-01	-3732
2002-01-01	5063
2002-04-01	-4028
2002-07-01	69
2002-10-01	1582
2003-01-01	-3810
2003-04-01	722
2003-07-01	293
2003-10-01	3806
2004-01-01	5367
2004-04-01	-3461
2004-07-01	1225
2004-10-01	3927
2005-01-01	7068
2005-04-01	-29500
2005-07-01	3114
2005-10-01	8105
2006-01-01	4972
2006-04-01	-16559
2006-07-01	4462
2006-10-01	12299
2007-01-01	8565
2007-04-01	16680
2007-07-01	-7665
2007-10-01	7485
2008-01-01	-5107
2008-04-01	4996
2008-07-01	-3469
2008-10-01	-11777
2009-01-01	-710
2009-04-01	-4058
2009-07-01	17514
2009-10-01	32409
2010-01-01	12242
2010-04-01	15358
2010-07-01	23375
2010-10-01	11880
2011-01-01	21013
2011-04-01	18773
2011-07-01	10460
2011-10-01	23620
2012-01-01	36051
2012-04-01	15628
2012-07-01	23041
2012-10-01	25854
2013-01-01	19534
2013-04-01	28313
2013-07-01	21529
2013-10-01	23285
2014-01-01	22902
2014-04-01	35223
2014-07-01	23203
2014-10-01	4659
2015-01-01	5700
2015-04-01	21939
2015-07-01	957
2015-10-01	-2311
2016-01-01	18515
2016-04-01	28280
2016-07-01	16185
2016-10-01	18184
2017-01-01	22761
2017-04-01	18441
2017-07-01	29925
2017-10-01	13770
2018-01-01	20490
2018-04-01	-6069