Quarter	Millions of US Dollars
1972-01-01	20
1972-04-01	40
1972-07-01	40
1972-10-01	40
1973-01-01	40
1973-04-01	40
1973-07-01	40
1973-10-01	40
1974-01-01	40
1974-04-01	40
1974-07-01	49
1974-10-01	49
1975-01-01	49
1975-04-01	49
1975-07-01	49
1975-10-01	49
1976-01-01	49
1976-04-01	49
1976-07-01	49
1976-10-01	63
1977-01-01	63
1977-04-01	63
1977-07-01	88
1977-10-01	88
1978-01-01	182
1978-04-01	186
1978-07-01	260
1978-10-01	281
1979-01-01	333
1979-04-01	330
1979-07-01	327
1979-10-01	321
1980-01-01	316
1980-04-01	311
1980-07-01	339
1980-10-01	343
1981-01-01	338
1981-04-01	330
1981-07-01	327
1981-10-01	332
1982-01-01	306
1982-04-01	303
1982-07-01	274
1982-10-01	286
1983-01-01	275
1983-04-01	274
1983-07-01	276
1983-10-01	278
1984-01-01	262
1984-04-01	255
1984-07-01	251
1984-10-01	248
1985-01-01	248
1985-04-01	249
1985-07-01	266
1985-10-01	241
1986-01-01	257
1986-04-01	271
1986-07-01	281
1986-10-01	262
1987-01-01	278
1987-04-01	276
1987-07-01	250
1987-10-01	289
1988-01-01	190
1988-04-01	180
1988-07-01	178
1988-10-01	188
1989-01-01	180
1989-04-01	170
1989-07-01	173
1989-10-01	170
1990-01-01	159
1990-04-01	163
1990-07-01	150
1990-10-01	134
1991-01-01	130
1991-04-01	132
1991-07-01	137
1991-10-01	145
1992-01-01	137
1992-04-01	144
1992-07-01	151
1992-10-01	145
1993-01-01	113
1993-04-01	123
1993-07-01	123
1993-10-01	116
1994-01-01	9
1994-04-01	9
1994-07-01	9
1994-10-01	9
1995-01-01	9
1995-04-01	9
1995-07-01	9
1995-10-01	9
1996-01-01	9
1996-04-01	9
1996-07-01	3231
1996-10-01	3231
1997-01-01	3731
1997-04-01	3731
1997-07-01	4431
1997-10-01	4431
1998-01-01	4431
1998-04-01	4731
1998-07-01	4731
1998-10-01	4118
1999-01-01	4618
1999-04-01	4618
1999-07-01	4618
1999-10-01	4618
2000-01-01	4618
2000-04-01	4592
2000-07-01	4942
2000-10-01	4942
2001-01-01	5692
2001-04-01	5547
2001-07-01	5504
2001-10-01	5150
2002-01-01	4803
2002-04-01	4803
2002-07-01	4844
2002-10-01	4873
2003-01-01	5041
2003-04-01	5041
2003-07-01	4994
2003-10-01	4994
2004-01-01	5173
2004-04-01	5148
2004-07-01	5139
2004-10-01	5739
2005-01-01	5739
2005-04-01	5739
2005-07-01	5989
2005-10-01	6950
2006-01-01	8313
2006-04-01	7703
2006-07-01	7657
2006-10-01	7657
2007-01-01	7657
2007-04-01	8107
2007-07-01	8107
2007-10-01	8107
2008-01-01	8107
2008-04-01	7742
2008-07-01	7742
2008-10-01	7742
2009-01-01	8065
2009-04-01	8065
2009-07-01	8065
2009-10-01	9065
2010-01-01	9065
2010-04-01	9065
2010-07-01	9065
2010-10-01	9065
2011-01-01	9144
2011-04-01	9158
2011-07-01	9182
2011-10-01	9178
2012-01-01	8998
2012-04-01	9014
2012-07-01	8747
2012-10-01	8694
2013-01-01	8652
2013-04-01	9382
2013-07-01	9388
2013-10-01	9858
2014-01-01	9864
2014-04-01	9872
2014-07-01	11091
2014-10-01	11059
2015-01-01	10838
2015-04-01	10830
2015-07-01	10837
2015-10-01	11286
2016-01-01	12311
2016-04-01	12345
2016-07-01	12351
2016-10-01	12296
2017-01-01	12313
2017-04-01	13734
2017-07-01	13733
2017-10-01	13732
2018-01-01	13754
2018-04-01	14939