Quarter	Millions of US Dollars
1973-01-01	20
1973-04-01	20
1973-07-01	20
1973-10-01	20
1974-01-01	20
1974-04-01	20
1974-07-01	20
1974-10-01	20
1975-01-01	20
1975-04-01	20
1975-07-01	20
1975-10-01	20
1976-01-01	20
1976-04-01	20
1976-07-01	20
1976-10-01	20
1977-01-01	20
1977-04-01	20
1977-07-01	20
1977-10-01	20
1978-01-01	20
1978-04-01	20
1978-07-01	20
1978-10-01	20
1979-01-01	20
1979-04-01	20
1979-07-01	20
1979-10-01	20
1980-01-01	20
1980-04-01	20
1980-07-01	20
1980-10-01	20
1981-01-01	20
1981-04-01	20
1981-07-01	20
1981-10-01	20
1982-01-01	20
1982-04-01	20
1982-07-01	20
1982-10-01	20
1983-01-01	20
1983-04-01	20
1983-07-01	20
1983-10-01	20
1984-01-01	20
1984-04-01	20
1984-07-01	20
1984-10-01	20
1985-01-01	20
1985-04-01	20
1985-07-01	20
1985-10-01	4
1986-01-01	4
1986-04-01	4
1986-07-01	43
1986-10-01	40
1987-01-01	43
1987-04-01	92
1987-07-01	92
1987-10-01	100
1988-01-01	98
1988-04-01	95
1988-07-01	95
1988-10-01	98
1989-01-01	95
1989-04-01	92
1989-07-01	93
1989-10-01	92
1990-01-01	88
1990-04-01	89
1990-07-01	93
1990-10-01	94
1991-01-01	93
1991-04-01	293
1991-07-01	295
1991-10-01	298
1992-01-01	295
1992-04-01	248
1992-07-01	250
1992-10-01	248
1993-01-01	252
1993-04-01	382
1993-07-01	382
1993-10-01	379
1994-01-01	731
1994-04-01	737
1994-07-01	677
1994-10-01	675
1995-01-01	690
1995-04-01	693
1995-07-01	798
1995-10-01	1038
1996-01-01	1506
1996-04-01	1884
1996-07-01	1873
1996-10-01	2149
1997-01-01	3095
1997-04-01	3129
1997-07-01	3093
1997-10-01	3052
1998-01-01	3423
1998-04-01	3934
1998-07-01	4635
1998-10-01	4724
1999-01-01	5071
1999-04-01	5542
1999-07-01	5631
1999-10-01	6120
2000-01-01	6842
2000-04-01	7087
2000-07-01	7273
2000-10-01	7471
2001-01-01	8121
2001-04-01	9645
2001-07-01	10165
2001-10-01	10911
2002-01-01	10666
2002-04-01	10295
2002-07-01	10661
2002-10-01	11316
2003-01-01	11503
2003-04-01	11060
2003-07-01	11517
2003-10-01	11711
2004-01-01	11476
2004-04-01	11452
2004-07-01	11995
2004-10-01	12639
2005-01-01	12953
2005-04-01	12951
2005-07-01	13134
2005-10-01	13220
2006-01-01	13008
2006-04-01	12393
2006-07-01	14614
2006-10-01	15164
2007-01-01	14751
2007-04-01	15659
2007-07-01	15963
2007-10-01	16028
2008-01-01	16052
2008-04-01	15615
2008-07-01	15177
2008-10-01	15106
2009-01-01	15712
2009-04-01	16327
2009-07-01	16726
2009-10-01	17998
2010-01-01	17492
2010-04-01	18081
2010-07-01	18650
2010-10-01	18408
2011-01-01	18499
2011-04-01	17882
2011-07-01	19622
2011-10-01	19431
2012-01-01	20103
2012-04-01	20080
2012-07-01	20674
2012-10-01	20408
2013-01-01	20108
2013-04-01	19866
2013-07-01	21491
2013-10-01	21431
2014-01-01	23351
2014-04-01	23554
2014-07-01	23190
2014-10-01	22514
2015-01-01	24759
2015-04-01	24739
2015-07-01	25677
2015-10-01	24657
2016-01-01	26225
2016-04-01	26296
2016-07-01	26336
2016-10-01	25984
2017-01-01	26956
2017-04-01	26945
2017-07-01	28461
2017-10-01	28457
2018-01-01	28671
2018-04-01	28445