Quarter	Millions of US Dollars
1971-01-01	15
1971-04-01	15
1971-07-01	15
1971-10-01	15
1972-01-01	88
1972-04-01	89
1972-07-01	116
1972-10-01	145
1973-01-01	207
1973-04-01	274
1973-07-01	281
1973-10-01	263
1974-01-01	288
1974-04-01	289
1974-07-01	296
1974-10-01	367
1975-01-01	532
1975-04-01	729
1975-07-01	891
1975-10-01	1426
1976-01-01	1940
1976-04-01	2207
1976-07-01	2505
1976-10-01	2841
1977-01-01	3564
1977-04-01	4451
1977-07-01	4694
1977-10-01	5844
1978-01-01	6914
1978-04-01	7628
1978-07-01	8431
1978-10-01	9287
1979-01-01	9750
1979-04-01	10215
1979-07-01	11142
1979-10-01	11255
1980-01-01	10766
1980-04-01	11676
1980-07-01	11421
1980-10-01	10700
1981-01-01	9915
1981-04-01	9117
1981-07-01	9243
1981-10-01	9796
1982-01-01	8803
1982-04-01	8384
1982-07-01	8405
1982-10-01	8676
1983-01-01	8306
1983-04-01	7760
1983-07-01	7738
1983-10-01	7340
1984-01-01	7520
1984-04-01	7073
1984-07-01	6846
1984-10-01	7007
1985-01-01	7068
1985-04-01	7222
1985-07-01	8568
1985-10-01	8151
1986-01-01	8848
1986-04-01	9927
1986-07-01	11701
1986-10-01	12736
1987-01-01	16196
1987-04-01	17270
1987-07-01	17798
1987-10-01	18753
1988-01-01	19796
1988-04-01	20903
1988-07-01	21189
1988-10-01	21118
1989-01-01	21470
1989-04-01	20886
1989-07-01	21059
1989-10-01	20921
1990-01-01	20436
1990-04-01	20284
1990-07-01	20521
1990-10-01	19878
1991-01-01	18343
1991-04-01	17803
1991-07-01	19294
1991-10-01	19696
1992-01-01	19719
1992-04-01	21802
1992-07-01	21951
1992-10-01	19786
1993-01-01	20081
1993-04-01	20824
1993-07-01	20397
1993-10-01	19187
1994-01-01	19111
1994-04-01	19388
1994-07-01	19823
1994-10-01	18889
1995-01-01	19808
1995-04-01	18986
1995-07-01	18735
1995-10-01	18364
1996-01-01	19082
1996-04-01	19388
1996-07-01	18565
1996-10-01	18576
1997-01-01	18519
1997-04-01	18420
1997-07-01	21659
1997-10-01	21271
1998-01-01	22761
1998-04-01	25798
1998-07-01	27209
1998-10-01	27790
1999-01-01	28832
1999-04-01	30260
1999-07-01	31390
1999-10-01	30370
2000-01-01	33208
2000-04-01	36187
2000-07-01	37257
2000-10-01	37411
2001-01-01	37770
2001-04-01	38596
2001-07-01	38831
2001-10-01	38630
2002-01-01	40471
2002-04-01	44761
2002-07-01	43568
2002-10-01	46577
2003-01-01	49374
2003-04-01	52617
2003-07-01	55771
2003-10-01	61241
2004-01-01	61902
2004-04-01	63945
2004-07-01	65301
2004-10-01	74949
2005-01-01	74900
2005-04-01	74572
2005-07-01	74673
2005-10-01	77559
2006-01-01	81944
2006-04-01	93482
2006-07-01	99974
2006-10-01	109501
2007-01-01	117918
2007-04-01	120111
2007-07-01	131103
2007-10-01	143754
2008-01-01	165309
2008-04-01	177413
2008-07-01	167502
2008-10-01	164907
2009-01-01	163785
2009-04-01	174834
2009-07-01	183475
2009-10-01	181762
2010-01-01	187071
2010-04-01	182349
2010-07-01	202375
2010-10-01	199502
2011-01-01	225133
2011-04-01	231176
2011-07-01	224343
2011-10-01	233540
2012-01-01	254543
2012-04-01	258251
2012-07-01	267819
2012-10-01	265406
2013-01-01	257703
2013-04-01	265230
2013-07-01	272612
2013-10-01	283317
2014-01-01	285117
2014-04-01	278182
2014-07-01	263572
2014-10-01	258441
2015-01-01	249271
2015-04-01	245673
2015-07-01	244546
2015-10-01	235128
2016-01-01	238575
2016-04-01	237126
2016-07-01	241364
2016-10-01	222475
2017-01-01	234158
2017-04-01	232831
2017-07-01	234022
2017-10-01	236459
2018-01-01	240846
2018-04-01	231344