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	0
1977-10-01	0
1978-01-01	0
1978-04-01	18
1978-07-01	18
1978-10-01	53
1979-01-01	128
1979-04-01	150
1979-07-01	162
1979-10-01	152
1980-01-01	161
1980-04-01	178
1980-07-01	166
1980-10-01	138
1981-01-01	137
1981-04-01	456
1981-07-01	461
1981-10-01	493
1982-01-01	856
1982-04-01	530
1982-07-01	522
1982-10-01	694
1983-01-01	395
1983-04-01	570
1983-07-01	779
1983-10-01	716
1984-01-01	776
1984-04-01	663
1984-07-01	593
1984-10-01	1563
1985-01-01	1559
1985-04-01	1689
1985-07-01	1857
1985-10-01	1094
1986-01-01	1375
1986-04-01	1353
1986-07-01	1418
1986-10-01	1370
1987-01-01	1223
1987-04-01	1755
1987-07-01	1918
1987-10-01	2226
1988-01-01	2548
1988-04-01	2010
1988-07-01	1907
1988-10-01	2106
1989-01-01	1627
1989-04-01	1948
1989-07-01	2119
1989-10-01	2095
1990-01-01	2031
1990-04-01	1544
1990-07-01	1247
1990-10-01	1081
1991-01-01	982
1991-04-01	954
1991-07-01	874
1991-10-01	2168
1992-01-01	2184
1992-04-01	2125
1992-07-01	3763
1992-10-01	3214
1993-01-01	2918
1993-04-01	3882
1993-07-01	3522
1993-10-01	3221
1994-01-01	3803
1994-04-01	4132
1994-07-01	4708
1994-10-01	4276
1995-01-01	4723
1995-04-01	6353
1995-07-01	6647
1995-10-01	7579
1996-01-01	7810
1996-04-01	6238
1996-07-01	12499
1996-10-01	13528
1997-01-01	12891
1997-04-01	13107
1997-07-01	7965
1997-10-01	31760
1998-01-01	30795
1998-04-01	32096
1998-07-01	31477
1998-10-01	8777
1999-01-01	11562
1999-04-01	18381
1999-07-01	19594
1999-10-01	20706
2000-01-01	22035
2000-04-01	52803
2000-07-01	55511
2000-10-01	64659
2001-01-01	63142
2001-04-01	30403
2001-07-01	29118
2001-10-01	22409
2002-01-01	33373
2002-04-01	40911
2002-07-01	46153
2002-10-01	46049
2003-01-01	40512
2003-04-01	34455
2003-07-01	34185
2003-10-01	32899
2004-01-01	29497
2004-04-01	65161
2004-07-01	72389
2004-10-01	77586
2005-01-01	77416
2005-04-01	51563
2005-07-01	41805
2005-10-01	43014
2006-01-01	42623
2006-04-01	28700
2006-07-01	31016
2006-10-01	25791
2007-01-01	32005
2007-04-01	32747
2007-07-01	28599
2007-10-01	35954
2008-01-01	32604
2008-04-01	37297
2008-07-01	37021
2008-10-01	29619
2009-01-01	32219
2009-04-01	23896
2009-07-01	27267
2009-10-01	27887
2010-01-01	24490
2010-04-01	25515
2010-07-01	28102
2010-10-01	27901
2011-01-01	26975
2011-04-01	24318
2011-07-01	24755
2011-10-01	26085
2012-01-01	33232
2012-04-01	37762
2012-07-01	33972
2012-10-01	30112
2013-01-01	43430
2013-04-01	50552
2013-07-01	55986
2013-10-01	68090
2014-01-01	58752
2014-04-01	54763
2014-07-01	54347
2014-10-01	67844
2015-01-01	60398
2015-04-01	53121
2015-07-01	57570
2015-10-01	35709
2016-01-01	40067
2016-04-01	65998
2016-07-01	58137
2016-10-01	62090
2017-01-01	61653
2017-04-01	45668
2017-07-01	49151
2017-10-01	46087
2018-01-01	50573
2018-04-01	58676