Quarter	Millions of US Dollars
1971-01-01	15
1971-04-01	44
1971-07-01	45
1971-10-01	46
1972-01-01	47
1972-04-01	47
1972-07-01	46
1972-10-01	46
1973-01-01	50
1973-04-01	56
1973-07-01	56
1973-10-01	52
1974-01-01	86
1974-04-01	168
1974-07-01	167
1974-10-01	319
1975-01-01	630
1975-04-01	914
1975-07-01	1070
1975-10-01	1454
1976-01-01	2154
1976-04-01	2686
1976-07-01	2892
1976-10-01	3242
1977-01-01	3585
1977-04-01	4088
1977-07-01	4432
1977-10-01	5081
1978-01-01	5664
1978-04-01	6274
1978-07-01	7565
1978-10-01	8241
1979-01-01	9238
1979-04-01	10395
1979-07-01	11836
1979-10-01	11798
1980-01-01	11036
1980-04-01	12486
1980-07-01	12852
1980-10-01	13262
1981-01-01	12947
1981-04-01	12896
1981-07-01	14554
1981-10-01	16103
1982-01-01	16355
1982-04-01	16255
1982-07-01	16656
1982-10-01	18776
1983-01-01	20227
1983-04-01	21656
1983-07-01	22398
1983-10-01	23683
1984-01-01	26890
1984-04-01	27217
1984-07-01	28335
1984-10-01	29269
1985-01-01	33022
1985-04-01	35648
1985-07-01	42125
1985-10-01	46054
1986-01-01	51321
1986-04-01	59033
1986-07-01	67392
1986-10-01	73638
1987-01-01	82221
1987-04-01	89793
1987-07-01	100022
1987-10-01	112986
1988-01-01	112633
1988-04-01	113700
1988-07-01	124983
1988-10-01	133364
1989-01-01	142620
1989-04-01	166463
1989-07-01	180790
1989-10-01	199267
1990-01-01	206372
1990-04-01	208737
1990-07-01	221402
1990-10-01	231146
1991-01-01	228951
1991-04-01	235779
1991-07-01	252818
1991-10-01	268432
1992-01-01	262677
1992-04-01	269393
1992-07-01	271698
1992-10-01	261367
1993-01-01	252136
1993-04-01	239564
1993-07-01	233104
1993-10-01	222618
1994-01-01	231585
1994-04-01	231130
1994-07-01	226644
1994-10-01	214662
1995-01-01	227848
1995-04-01	222989
1995-07-01	197716
1995-10-01	190465
1996-01-01	182429
1996-04-01	174899
1996-07-01	168969
1996-10-01	157623
1997-01-01	144366
1997-04-01	141983
1997-07-01	131026
1997-10-01	117777
1998-01-01	104854
1998-04-01	93826
1998-07-01	90423
1998-10-01	94666
1999-01-01	88189
1999-04-01	85436
1999-07-01	89413
1999-10-01	82413
2000-01-01	71723
2000-04-01	67554
2000-07-01	62566
2000-10-01	59004
2001-01-01	53032
2001-04-01	50134
2001-07-01	50088
2001-10-01	46003
2002-01-01	45662
2002-04-01	51761
2002-07-01	48555
2002-10-01	46871
2003-01-01	44121
2003-04-01	44676
2003-07-01	42879
2003-10-01	50824
2004-01-01	53943
2004-04-01	57148
2004-07-01	56076
2004-10-01	61611
2005-01-01	59967
2005-04-01	58340
2005-07-01	56920
2005-10-01	55549
2006-01-01	55704
2006-04-01	57362
2006-07-01	54569
2006-10-01	55215
2007-01-01	52351
2007-04-01	50106
2007-07-01	52538
2007-10-01	54384
2008-01-01	58877
2008-04-01	58477
2008-07-01	58362
2008-10-01	60956
2009-01-01	53927
2009-04-01	48904
2009-07-01	49934
2009-10-01	47740
2010-01-01	45023
2010-04-01	43831
2010-07-01	48738
2010-10-01	47652
2011-01-01	45834
2011-04-01	41672
2011-07-01	39409
2011-10-01	39179
2012-01-01	37222
2012-04-01	37078
2012-07-01	42162
2012-10-01	40715
2013-01-01	37367
2013-04-01	39516
2013-07-01	45548
2013-10-01	44252
2014-01-01	43077
2014-04-01	48311
2014-07-01	49230
2014-10-01	49473
2015-01-01	46496
2015-04-01	47269
2015-07-01	51923
2015-10-01	52724
2016-01-01	57822
2016-04-01	65909
2016-07-01	65806
2016-10-01	60253
2017-01-01	67624
2017-04-01	69368
2017-07-01	88008
2017-10-01	91142
2018-01-01	97060
2018-04-01	96016