Quarter	Millions of US Dollars
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	32
1978-04-01	90
1978-07-01	130
1978-10-01	150
1979-01-01	109
1979-04-01	78
1979-07-01	58
1979-10-01	78
1980-01-01	79
1980-04-01	118
1980-07-01	115
1980-10-01	65
1981-01-01	158
1981-04-01	123
1981-07-01	141
1981-10-01	148
1982-01-01	98
1982-04-01	128
1982-07-01	159
1982-10-01	231
1983-01-01	161
1983-04-01	107
1983-07-01	57
1983-10-01	21
1984-01-01	33
1984-04-01	30
1984-07-01	48
1984-10-01	57
1985-01-01	90
1985-04-01	160
1985-07-01	164
1985-10-01	177
1986-01-01	209
1986-04-01	129
1986-07-01	216
1986-10-01	207
1987-01-01	123
1987-04-01	122
1987-07-01	111
1987-10-01	86
1988-01-01	183
1988-04-01	199
1988-07-01	119
1988-10-01	167
1989-01-01	134
1989-04-01	145
1989-07-01	165
1989-10-01	197
1990-01-01	160
1990-04-01	176
1990-07-01	166
1990-10-01	160
1991-01-01	113
1991-04-01	51
1991-07-01	124
1991-10-01	74
1992-01-01	83
1992-04-01	98
1992-07-01	49
1992-10-01	179
1993-01-01	217
1993-04-01	244
1993-07-01	568
1993-10-01	447
1994-01-01	780
1994-04-01	992
1994-07-01	676
1994-10-01	1120
1995-01-01	888
1995-04-01	1072
1995-07-01	451
1995-10-01	1120
1996-01-01	1228
1996-04-01	1228
1996-07-01	651
1996-10-01	675
1997-01-01	854
1997-04-01	1397
1997-07-01	670
1997-10-01	1483
1998-01-01	1170
1998-04-01	980
1998-07-01	1230
1998-10-01	934
1999-01-01	1155
1999-04-01	1804
1999-07-01	1104
1999-10-01	2940
2000-01-01	2542
2000-04-01	5378
2000-07-01	7824
2000-10-01	17099
2001-01-01	12217
2001-04-01	15174
2001-07-01	12718
2001-10-01	10947
2002-01-01	9040
2002-04-01	7544
2002-07-01	9394
2002-10-01	9617
2003-01-01	18008
2003-04-01	21234
2003-07-01	14551
2003-10-01	13181
2004-01-01	15477
2004-04-01	15413
2004-07-01	17257
2004-10-01	17069
2005-01-01	16730
2005-04-01	17318
2005-07-01	12786
2005-10-01	9117
2006-01-01	12670
2006-04-01	20226
2006-07-01	17478
2006-10-01	12418
2007-01-01	12033
2007-04-01	13331
2007-07-01	15244
2007-10-01	12130
2008-01-01	15359
2008-04-01	26877
2008-07-01	26904
2008-10-01	25283
2009-01-01	16695
2009-04-01	19168
2009-07-01	16084
2009-10-01	12658
2010-01-01	11153
2010-04-01	16132
2010-07-01	17233
2010-10-01	12786
2011-01-01	14992
2011-04-01	22806
2011-07-01	22157
2011-10-01	18600
2012-01-01	13599
2012-04-01	19368
2012-07-01	19734
2012-10-01	15800
2013-01-01	22058
2013-04-01	26754
2013-07-01	27635
2013-10-01	27467
2014-01-01	26786
2014-04-01	25454
2014-07-01	22547
2014-10-01	22264
2015-01-01	17865
2015-04-01	24159
2015-07-01	25141
2015-10-01	17997
2016-01-01	29180
2016-04-01	30399
2016-07-01	27261
2016-10-01	26879
2017-01-01	27521
2017-04-01	23672
2017-07-01	26218
2017-10-01	23389
2018-01-01	24736
2018-04-01	27097