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	0
1977-01-01	0
1977-04-01	0
1977-07-01	30
1977-10-01	98
1978-01-01	127
1978-04-01	188
1978-07-01	197
1978-10-01	203
1979-01-01	394
1979-04-01	553
1979-07-01	628
1979-10-01	739
1980-01-01	620
1980-04-01	765
1980-07-01	764
1980-10-01	731
1981-01-01	761
1981-04-01	995
1981-07-01	1442
1981-10-01	1458
1982-01-01	1868
1982-04-01	1633
1982-07-01	1362
1982-10-01	1734
1983-01-01	1523
1983-04-01	1725
1983-07-01	2001
1983-10-01	1822
1984-01-01	1779
1984-04-01	1557
1984-07-01	1548
1984-10-01	3546
1985-01-01	3734
1985-04-01	3952
1985-07-01	4117
1985-10-01	2575
1986-01-01	2895
1986-04-01	2887
1986-07-01	3080
1986-10-01	3182
1987-01-01	3625
1987-04-01	4507
1987-07-01	5045
1987-10-01	5549
1988-01-01	5331
1988-04-01	4548
1988-07-01	4113
1988-10-01	3934
1989-01-01	3333
1989-04-01	4171
1989-07-01	4542
1989-10-01	5120
1990-01-01	5920
1990-04-01	4569
1990-07-01	4082
1990-10-01	3467
1991-01-01	2931
1991-04-01	3306
1991-07-01	3686
1991-10-01	6086
1992-01-01	6886
1992-04-01	7960
1992-07-01	10309
1992-10-01	10107
1993-01-01	9260
1993-04-01	9433
1993-07-01	17675
1993-10-01	17752
1994-01-01	21575
1994-04-01	22668
1994-07-01	24486
1994-10-01	24614
1995-01-01	21087
1995-04-01	24392
1995-07-01	29924
1995-10-01	33555
1996-01-01	34218
1996-04-01	33568
1996-07-01	35729
1996-10-01	41539
1997-01-01	40668
1997-04-01	43519
1997-07-01	40685
1997-10-01	60939
1998-01-01	64349
1998-04-01	66671
1998-07-01	63025
1998-10-01	42809
1999-01-01	40755
1999-04-01	47432
1999-07-01	51211
1999-10-01	51059
2000-01-01	53144
2000-04-01	85955
2000-07-01	87199
2000-10-01	95124
2001-01-01	95501
2001-04-01	63627
2001-07-01	62351
2001-10-01	57831
2002-01-01	64584
2002-04-01	72058
2002-07-01	74088
2002-10-01	75232
2003-01-01	74551
2003-04-01	72366
2003-07-01	75200
2003-10-01	73958
2004-01-01	67679
2004-04-01	99535
2004-07-01	107112
2004-10-01	112695
2005-01-01	112585
2005-04-01	86607
2005-07-01	73986
2005-10-01	77702
2006-01-01	81680
2006-04-01	70314
2006-07-01	81318
2006-10-01	78109
2007-01-01	88127
2007-04-01	91373
2007-07-01	85311
2007-10-01	95406
2008-01-01	97692
2008-04-01	103755
2008-07-01	106635
2008-10-01	95146
2009-01-01	99533
2009-04-01	95850
2009-07-01	99922
2009-10-01	96508
2010-01-01	89655
2010-04-01	94151
2010-07-01	104454
2010-10-01	102323
2011-01-01	109242
2011-04-01	112677
2011-07-01	105009
2011-10-01	115823
2012-01-01	123227
2012-04-01	115718
2012-07-01	120979
2012-10-01	116039
2013-01-01	129312
2013-04-01	153339
2013-07-01	170812
2013-10-01	182563
2014-01-01	179159
2014-04-01	164104
2014-07-01	162410
2014-10-01	188006
2015-01-01	186183
2015-04-01	192346
2015-07-01	194884
2015-10-01	172188
2016-01-01	176340
2016-04-01	213315
2016-07-01	206794
2016-10-01	214115
2017-01-01	214861
2017-04-01	200707
2017-07-01	203182
2017-10-01	195290
2018-01-01	198654
2018-04-01	217244