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	0
1978-07-01	17
1978-10-01	62
1979-01-01	61
1979-04-01	60
1979-07-01	96
1979-10-01	108
1980-01-01	95
1980-04-01	106
1980-07-01	146
1980-10-01	85
1981-01-01	78
1981-04-01	100
1981-07-01	27
1981-10-01	27
1982-01-01	60
1982-04-01	49
1982-07-01	70
1982-10-01	75
1983-01-01	70
1983-04-01	162
1983-07-01	137
1983-10-01	133
1984-01-01	106
1984-04-01	0
1984-07-01	20
1984-10-01	197
1985-01-01	414
1985-04-01	416
1985-07-01	411
1985-10-01	463
1986-01-01	568
1986-04-01	644
1986-07-01	779
1986-10-01	842
1987-01-01	838
1987-04-01	826
1987-07-01	1119
1987-10-01	898
1988-01-01	1145
1988-04-01	1059
1988-07-01	636
1988-10-01	743
1989-01-01	300
1989-04-01	271
1989-07-01	667
1989-10-01	554
1990-01-01	540
1990-04-01	549
1990-07-01	224
1990-10-01	586
1991-01-01	403
1991-04-01	829
1991-07-01	832
1991-10-01	762
1992-01-01	947
1992-04-01	882
1992-07-01	1006
1992-10-01	1126
1993-01-01	1615
1993-04-01	1290
1993-07-01	1769
1993-10-01	1906
1994-01-01	1836
1994-04-01	2079
1994-07-01	2026
1994-10-01	2020
1995-01-01	3275
1995-04-01	3086
1995-07-01	2757
1995-10-01	2275
1996-01-01	1890
1996-04-01	3319
1996-07-01	2406
1996-10-01	4239
1997-01-01	4998
1997-04-01	6750
1997-07-01	8712
1997-10-01	9199
1998-01-01	11884
1998-04-01	13306
1998-07-01	17255
1998-10-01	17037
1999-01-01	19926
1999-04-01	21544
1999-07-01	21436
1999-10-01	25643
2000-01-01	26259
2000-04-01	29537
2000-07-01	27422
2000-10-01	30686
2001-01-01	32282
2001-04-01	35285
2001-07-01	36333
2001-10-01	40615
2002-01-01	42580
2002-04-01	46517
2002-07-01	43999
2002-10-01	44438
2003-01-01	49884
2003-04-01	56836
2003-07-01	55501
2003-10-01	61396
2004-01-01	70262
2004-04-01	68860
2004-07-01	77635
2004-10-01	102421
2005-01-01	107792
2005-04-01	106292
2005-07-01	112266
2005-10-01	123618
2006-01-01	139427
2006-04-01	148621
2006-07-01	159242
2006-10-01	175226
2007-01-01	194481
2007-04-01	203737
2007-07-01	220553
2007-10-01	230431
2008-01-01	245907
2008-04-01	250992
2008-07-01	239862
2008-10-01	217851
2009-01-01	211131
2009-04-01	216253
2009-07-01	263524
2009-10-01	239034
2010-01-01	220718
2010-04-01	198109
2010-07-01	174906
2010-10-01	158723
2011-01-01	128208
2011-04-01	141857
2011-07-01	133754
2011-10-01	146924
2012-01-01	189904
2012-04-01	179164
2012-07-01	172078
2012-10-01	172178
2013-01-01	152693
2013-04-01	138710
2013-07-01	147618
2013-10-01	186629
2014-01-01	184140
2014-04-01	184979
2014-07-01	173523
2014-10-01	130947
2015-01-01	95432
2015-04-01	95006
2015-07-01	82003
2015-10-01	94448
2016-01-01	123172
2016-04-01	125825
2016-07-01	121076
2016-10-01	109295
2017-01-01	91008
2017-04-01	78672
2017-07-01	85813
2017-10-01	90017
2018-01-01	80862
2018-04-01	75994