Quarter	Millions of US Dollars
1971-01-01	0
1971-04-01	0
1971-07-01	0
1971-10-01	0
1972-01-01	0
1972-04-01	0
1972-07-01	0
1972-10-01	0
1973-01-01	0
1973-04-01	0
1973-07-01	0
1973-10-01	0
1974-01-01	0
1974-04-01	0
1974-07-01	0
1974-10-01	0
1975-01-01	0
1975-04-01	0
1975-07-01	0
1975-10-01	0
1976-01-01	0
1976-04-01	0
1976-07-01	0
1976-10-01	10
1977-01-01	10
1977-04-01	10
1977-07-01	10
1977-10-01	0
1978-01-01	16
1978-04-01	59
1978-07-01	71
1978-10-01	267
1979-01-01	557
1979-04-01	758
1979-07-01	999
1979-10-01	1134
1980-01-01	1053
1980-04-01	1474
1980-07-01	1396
1980-10-01	1232
1981-01-01	1407
1981-04-01	1137
1981-07-01	1245
1981-10-01	1308
1982-01-01	1319
1982-04-01	1306
1982-07-01	1266
1982-10-01	1523
1983-01-01	1679
1983-04-01	2523
1983-07-01	2723
1983-10-01	2698
1984-01-01	2755
1984-04-01	2071
1984-07-01	2260
1984-10-01	2908
1985-01-01	2983
1985-04-01	3171
1985-07-01	4003
1985-10-01	3913
1986-01-01	4877
1986-04-01	5315
1986-07-01	5611
1986-10-01	6495
1987-01-01	7622
1987-04-01	8738
1987-07-01	8956
1987-10-01	11013
1988-01-01	11023
1988-04-01	10319
1988-07-01	12391
1988-10-01	13584
1989-01-01	13740
1989-04-01	14422
1989-07-01	14761
1989-10-01	17240
1990-01-01	18760
1990-04-01	22663
1990-07-01	26654
1990-10-01	29183
1991-01-01	33650
1991-04-01	37856
1991-07-01	52274
1991-10-01	57732
1992-01-01	73183
1992-04-01	93163
1992-07-01	102765
1992-10-01	106955
1993-01-01	94705
1993-04-01	75993
1993-07-01	77110
1993-10-01	69823
1994-01-01	67013
1994-04-01	67417
1994-07-01	76621
1994-10-01	72496
1995-01-01	79713
1995-04-01	82852
1995-07-01	70145
1995-10-01	74413
1996-01-01	72469
1996-04-01	76041
1996-07-01	73718
1996-10-01	87213
1997-01-01	89177
1997-04-01	90740
1997-07-01	82556
1997-10-01	68973
1998-01-01	54802
1998-04-01	44801
1998-07-01	45852
1998-10-01	58189
1999-01-01	61871
1999-04-01	64109
1999-07-01	77999
1999-10-01	75875
2000-01-01	65819
2000-04-01	64437
2000-07-01	57419
2000-10-01	57462
2001-01-01	54229
2001-04-01	53332
2001-07-01	54533
2001-10-01	51646
2002-01-01	51579
2002-04-01	54972
2002-07-01	53018
2002-10-01	51833
2003-01-01	49951
2003-04-01	50251
2003-07-01	49543
2003-10-01	47665
2004-01-01	47205
2004-04-01	50609
2004-07-01	49182
2004-10-01	50578
2005-01-01	50892
2005-04-01	44481
2005-07-01	42725
2005-10-01	43814
2006-01-01	49375
2006-04-01	51421
2006-07-01	55097
2006-10-01	49593
2007-01-01	49312
2007-04-01	47491
2007-07-01	39446
2007-10-01	48032
2008-01-01	54126
2008-04-01	67169
2008-07-01	64131
2008-10-01	67110
2009-01-01	66736
2009-04-01	74502
2009-07-01	75208
2009-10-01	67849
2010-01-01	65977
2010-04-01	61508
2010-07-01	73614
2010-10-01	78494
2011-01-01	85573
2011-04-01	74727
2011-07-01	75297
2011-10-01	74425
2012-01-01	83326
2012-04-01	82163
2012-07-01	86127
2012-10-01	82795
2013-01-01	81334
2013-04-01	87297
2013-07-01	87133
2013-10-01	93609
2014-01-01	90566
2014-04-01	96898
2014-07-01	101742
2014-10-01	97294
2015-01-01	88139
2015-04-01	92727
2015-07-01	95301
2015-10-01	100947
2016-01-01	116425
2016-04-01	111680
2016-07-01	106826
2016-10-01	104172
2017-01-01	107128
2017-04-01	112082
2017-07-01	117590
2017-10-01	120509
2018-01-01	124388
2018-04-01	125110