Quarter	Millions of US Dollars
1966-01-01	15
1966-04-01	15
1966-07-01	15
1966-10-01	15
1967-01-01	15
1967-04-01	15
1967-07-01	15
1967-10-01	15
1968-01-01	15
1968-04-01	15
1968-07-01	15
1968-10-01	15
1969-01-01	15
1969-04-01	15
1969-07-01	15
1969-10-01	15
1970-01-01	15
1970-04-01	15
1970-07-01	15
1970-10-01	15
1971-01-01	15
1971-04-01	15
1971-07-01	15
1971-10-01	15
1972-01-01	65
1972-04-01	81
1972-07-01	80
1972-10-01	79
1973-01-01	87
1973-04-01	97
1973-07-01	98
1973-10-01	89
1974-01-01	93
1974-04-01	92
1974-07-01	125
1974-10-01	220
1975-01-01	257
1975-04-01	344
1975-07-01	590
1975-10-01	633
1976-01-01	642
1976-04-01	793
1976-07-01	885
1976-10-01	1087
1977-01-01	1104
1977-04-01	1354
1977-07-01	1554
1977-10-01	1795
1978-01-01	2182
1978-04-01	2358
1978-07-01	2572
1978-10-01	2900
1979-01-01	2912
1979-04-01	3082
1979-07-01	3383
1979-10-01	3343
1980-01-01	3040
1980-04-01	3417
1980-07-01	3354
1980-10-01	3210
1981-01-01	3131
1981-04-01	3027
1981-07-01	3082
1981-10-01	3502
1982-01-01	3740
1982-04-01	3782
1982-07-01	3731
1982-10-01	4436
1983-01-01	4612
1983-04-01	4425
1983-07-01	4349
1983-10-01	4284
1984-01-01	4494
1984-04-01	4385
1984-07-01	4269
1984-10-01	4754
1985-01-01	4834
1985-04-01	5112
1985-07-01	6198
1985-10-01	6407
1986-01-01	7265
1986-04-01	8131
1986-07-01	9385
1986-10-01	9752
1987-01-01	12114
1987-04-01	12704
1987-07-01	12968
1987-10-01	14189
1988-01-01	13380
1988-04-01	13096
1988-07-01	12772
1988-10-01	13743
1989-01-01	13227
1989-04-01	12833
1989-07-01	12593
1989-10-01	12355
1990-01-01	12097
1990-04-01	12414
1990-07-01	13473
1990-10-01	13746
1991-01-01	13336
1991-04-01	13133
1991-07-01	13166
1991-10-01	12556
1992-01-01	12346
1992-04-01	11866
1992-07-01	11767
1992-10-01	10580
1993-01-01	9938
1993-04-01	9773
1993-07-01	9536
1993-10-01	9381
1994-01-01	9624
1994-04-01	9991
1994-07-01	10358
1994-10-01	10146
1995-01-01	10436
1995-04-01	10038
1995-07-01	9606
1995-10-01	9453
1996-01-01	9471
1996-04-01	8929
1996-07-01	8159
1996-10-01	8332
1997-01-01	7787
1997-04-01	8208
1997-07-01	7944
1997-10-01	8547
1998-01-01	8620
1998-04-01	8011
1998-07-01	7890
1998-10-01	8297
1999-01-01	8078
1999-04-01	7449
1999-07-01	8118
1999-10-01	7998
2000-01-01	8132
2000-04-01	8445
2000-07-01	7903
2000-10-01	8394
2001-01-01	7951
2001-04-01	8564
2001-07-01	8314
2001-10-01	8347
2002-01-01	8046
2002-04-01	9185
2002-07-01	9347
2002-10-01	8752
2003-01-01	10488
2003-04-01	10545
2003-07-01	9846
2003-10-01	10359
2004-01-01	11797
2004-04-01	12434
2004-07-01	14759
2004-10-01	18772
2005-01-01	19849
2005-04-01	19148
2005-07-01	19082
2005-10-01	18633
2006-01-01	18033
2006-04-01	18780
2006-07-01	18594
2006-10-01	17671
2007-01-01	16294
2007-04-01	16164
2007-07-01	16823
2007-10-01	18934
2008-01-01	20919
2008-04-01	16914
2008-07-01	14102
2008-10-01	12183
2009-01-01	10709
2009-04-01	10932
2009-07-01	8708
2009-10-01	10525
2010-01-01	9190
2010-04-01	9042
2010-07-01	9221
2010-10-01	13007
2011-01-01	15954
2011-04-01	15844
2011-07-01	18485
2011-10-01	19282
2012-01-01	20715
2012-04-01	20315
2012-07-01	22196
2012-10-01	21800
2013-01-01	22132
2013-04-01	22110
2013-07-01	22920
2013-10-01	23689
2014-01-01	20586
2014-04-01	21636
2014-07-01	20881
2014-10-01	20417
2015-01-01	19946
2015-04-01	20218
2015-07-01	20118
2015-10-01	20165
2016-01-01	20777
2016-04-01	24474
2016-07-01	23178
2016-10-01	20081
2017-01-01	20390
2017-04-01	21038
2017-07-01	22673
2017-10-01	24412
2018-01-01	24614
2018-04-01	23786