Quarter	Millions of US Dollars
1968-04-01	0
1968-07-01	0
1968-10-01	0
1969-01-01	0
1969-04-01	0
1969-07-01	0
1969-10-01	0
1970-01-01	0
1970-04-01	0
1970-07-01	0
1970-10-01	0
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	23
1976-01-01	24
1976-04-01	24
1976-07-01	25
1976-10-01	0
1977-01-01	0
1977-04-01	4
1977-07-01	11
1977-10-01	25
1978-01-01	54
1978-04-01	57
1978-07-01	87
1978-10-01	78
1979-01-01	248
1979-04-01	493
1979-07-01	509
1979-10-01	627
1980-01-01	649
1980-04-01	947
1980-07-01	1129
1980-10-01	1418
1981-01-01	1276
1981-04-01	953
1981-07-01	905
1981-10-01	1195
1982-01-01	1671
1982-04-01	1964
1982-07-01	2135
1982-10-01	1603
1983-01-01	1217
1983-04-01	936
1983-07-01	919
1983-10-01	1086
1984-01-01	1947
1984-04-01	2507
1984-07-01	3770
1984-10-01	6901
1985-01-01	7806
1985-04-01	8460
1985-07-01	9392
1985-10-01	7528
1986-01-01	7529
1986-04-01	7427
1986-07-01	6329
1986-10-01	5934
1987-01-01	4560
1987-04-01	3484
1987-07-01	5117
1987-10-01	5911
1988-01-01	5928
1988-04-01	6624
1988-07-01	4949
1988-10-01	4908
1989-01-01	5753
1989-04-01	5807
1989-07-01	5701
1989-10-01	6637
1990-01-01	6593
1990-04-01	7744
1990-07-01	10066
1990-10-01	10225
1991-01-01	10739
1991-04-01	12196
1991-07-01	13551
1991-10-01	14846
1992-01-01	15362
1992-04-01	18977
1992-07-01	19817
1992-10-01	19675
1993-01-01	20443
1993-04-01	17605
1993-07-01	24972
1993-10-01	22372
1994-01-01	22521
1994-04-01	21436
1994-07-01	23218
1994-10-01	24457
1995-01-01	27247
1995-04-01	27939
1995-07-01	27447
1995-10-01	28850
1996-01-01	27479
1996-04-01	33540
1996-07-01	25442
1996-10-01	30577
1997-01-01	32458
1997-04-01	28781
1997-07-01	32774
1997-10-01	33328
1998-01-01	41215
1998-04-01	38522
1998-07-01	42645
1998-10-01	44214
1999-01-01	39597
1999-04-01	41227
1999-07-01	44570
1999-10-01	44982
2000-01-01	49136
2000-04-01	48041
2000-07-01	50054
2000-10-01	59021
2001-01-01	69991
2001-04-01	64052
2001-07-01	70277
2001-10-01	66986
2002-01-01	60253
2002-04-01	76742
2002-07-01	76806
2002-10-01	84803
2003-01-01	91046
2003-04-01	99396
2003-07-01	108954
2003-10-01	120447
2004-01-01	120072
2004-04-01	126977
2004-07-01	130850
2004-10-01	142792
2005-01-01	142479
2005-04-01	135133
2005-07-01	146479
2005-10-01	148332
2006-01-01	157089
2006-04-01	164282
2006-07-01	163557
2006-10-01	180233
2007-01-01	185495
2007-04-01	213277
2007-07-01	215548
2007-10-01	252108
2008-01-01	306643
2008-04-01	327977
2008-07-01	299288
2008-10-01	268243
2009-01-01	243076
2009-04-01	288085
2009-07-01	300661
2009-10-01	316322
2010-01-01	318010
2010-04-01	288848
2010-07-01	316915
2010-10-01	289623
2011-01-01	356014
2011-04-01	353862
2011-07-01	323764
2011-10-01	321583
2012-01-01	332646
2012-04-01	297680
2012-07-01	321541
2012-10-01	314675
2013-01-01	323026
2013-04-01	351424
2013-07-01	360709
2013-10-01	363198
2014-01-01	371620
2014-04-01	358635
2014-07-01	345338
2014-10-01	309548
2015-01-01	286706
2015-04-01	279851
2015-07-01	252539
2015-10-01	231844
2016-01-01	261742
2016-04-01	265933
2016-07-01	280348
2016-10-01	278995
2017-01-01	283368
2017-04-01	267376
2017-07-01	266040
2017-10-01	265129
2018-01-01	257575
2018-04-01	255019