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	4554
1983-04-01	4367
1983-07-01	4292
1983-10-01	4226
1984-01-01	4436
1984-04-01	4328
1984-07-01	4213
1984-10-01	4748
1985-01-01	4863
1985-04-01	5156
1985-07-01	6467
1985-10-01	6808
1986-01-01	7734
1986-04-01	8687
1986-07-01	10169
1986-10-01	10787
1987-01-01	13455
1987-04-01	14315
1987-07-01	14953
1987-10-01	16898
1988-01-01	16121
1988-04-01	15757
1988-07-01	15296
1988-10-01	16371
1989-01-01	15800
1989-04-01	15323
1989-07-01	15197
1989-10-01	14886
1990-01-01	14656
1990-04-01	15059
1990-07-01	16272
1990-10-01	16600
1991-01-01	15969
1991-04-01	15584
1991-07-01	15760
1991-10-01	14933
1992-01-01	14403
1992-04-01	13715
1992-07-01	13410
1992-10-01	11951
1993-01-01	11199
1993-04-01	11028
1993-07-01	10668
1993-10-01	10225
1994-01-01	10570
1994-04-01	10421
1994-07-01	10356
1994-10-01	10376
1995-01-01	10148
1995-04-01	9955
1995-07-01	9334
1995-10-01	9460
1996-01-01	9168
1996-04-01	9529
1996-07-01	8660
1996-10-01	8859
1997-01-01	8415
1997-04-01	8635
1997-07-01	8373
1997-10-01	8892
1998-01-01	8936
1998-04-01	8570
1998-07-01	8527
1998-10-01	8743
1999-01-01	8399
1999-04-01	7998
1999-07-01	8409
1999-10-01	8254
2000-01-01	8184
2000-04-01	8629
2000-07-01	7926
2000-10-01	8366
2001-01-01	8330
2001-04-01	8971
2001-07-01	8771
2001-10-01	8655
2002-01-01	8381
2002-04-01	9821
2002-07-01	10170
2002-10-01	9351
2003-01-01	10432
2003-04-01	10071
2003-07-01	9549
2003-10-01	9635
2004-01-01	9795
2004-04-01	9843
2004-07-01	10264
2004-10-01	11405
2005-01-01	9911
2005-04-01	8881
2005-07-01	8803
2005-10-01	7576
2006-01-01	6824
2006-04-01	6945
2006-07-01	6902
2006-10-01	7083
2007-01-01	7116
2007-04-01	8164
2007-07-01	7886
2007-10-01	10036
2008-01-01	10035
2008-04-01	9400
2008-07-01	8436
2008-10-01	7676
2009-01-01	7466
2009-04-01	7807
2009-07-01	7799
2009-10-01	9923
2010-01-01	9731
2010-04-01	10099
2010-07-01	10741
2010-10-01	14369
2011-01-01	17333
2011-04-01	16699
2011-07-01	19243
2011-10-01	19931
2012-01-01	21923
2012-04-01	21422
2012-07-01	22864
2012-10-01	23753
2013-01-01	24432
2013-04-01	22619
2013-07-01	23352
2013-10-01	23778
2014-01-01	19695
2014-04-01	20790
2014-07-01	20473
2014-10-01	20119
2015-01-01	19986
2015-04-01	20384
2015-07-01	20477
2015-10-01	20225
2016-01-01	20201
2016-04-01	23199
2016-07-01	20511
2016-10-01	14860
2017-01-01	14569
2017-04-01	14835
2017-07-01	14889
2017-10-01	15926
2018-01-01	16203
2018-04-01	15969