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	136
1973-01-01	196
1973-04-01	262
1973-07-01	269
1973-10-01	252
1974-01-01	277
1974-04-01	278
1974-07-01	285
1974-10-01	355
1975-01-01	519
1975-04-01	717
1975-07-01	880
1975-10-01	1415
1976-01-01	1929
1976-04-01	2196
1976-07-01	2493
1976-10-01	2869
1977-01-01	3644
1977-04-01	4532
1977-07-01	4776
1977-10-01	5931
1978-01-01	7002
1978-04-01	7715
1978-07-01	8522
1978-10-01	9380
1979-01-01	9813
1979-04-01	10278
1979-07-01	11177
1979-10-01	11308
1980-01-01	10755
1980-04-01	11657
1980-07-01	11403
1980-10-01	10666
1981-01-01	9926
1981-04-01	9130
1981-07-01	9255
1981-10-01	9723
1982-01-01	8734
1982-04-01	8319
1982-07-01	8341
1982-10-01	8609
1983-01-01	8258
1983-04-01	7711
1983-07-01	7716
1983-10-01	7318
1984-01-01	7498
1984-04-01	7051
1984-07-01	6898
1984-10-01	7059
1985-01-01	7120
1985-04-01	7349
1985-07-01	8783
1985-10-01	8485
1986-01-01	9277
1986-04-01	10464
1986-07-01	12655
1986-10-01	13937
1987-01-01	17931
1987-04-01	19022
1987-07-01	19624
1987-10-01	20714
1988-01-01	21696
1988-04-01	22832
1988-07-01	23101
1988-10-01	23108
1989-01-01	23562
1989-04-01	22993
1989-07-01	23130
1989-10-01	23314
1990-01-01	22523
1990-04-01	22522
1990-07-01	22859
1990-10-01	22249
1991-01-01	20535
1991-04-01	19995
1991-07-01	21550
1991-10-01	22049
1992-01-01	21333
1992-04-01	23441
1992-07-01	23610
1992-10-01	21394
1993-01-01	21548
1993-04-01	21929
1993-07-01	21466
1993-10-01	20199
1994-01-01	20138
1994-04-01	20331
1994-07-01	20683
1994-10-01	19764
1995-01-01	20658
1995-04-01	19761
1995-07-01	19512
1995-10-01	19242
1996-01-01	20110
1996-04-01	20316
1996-07-01	19493
1996-10-01	19503
1997-01-01	19513
1997-04-01	19415
1997-07-01	22796
1997-10-01	22204
1998-01-01	23700
1998-04-01	27380
1998-07-01	29232
1998-10-01	29699
1999-01-01	31336
1999-04-01	32455
1999-07-01	33623
1999-10-01	32648
2000-01-01	35279
2000-04-01	38370
2000-07-01	39561
2000-10-01	40037
2001-01-01	40169
2001-04-01	40998
2001-07-01	40794
2001-10-01	41136
2002-01-01	42307
2002-04-01	46250
2002-07-01	45167
2002-10-01	48088
2003-01-01	51682
2003-04-01	54862
2003-07-01	58043
2003-10-01	63638
2004-01-01	64253
2004-04-01	66250
2004-07-01	66584
2004-10-01	76145
2005-01-01	75382
2005-04-01	75622
2005-07-01	75705
2005-10-01	78571
2006-01-01	83080
2006-04-01	94365
2006-07-01	101134
2006-10-01	109732
2007-01-01	118042
2007-04-01	120331
2007-07-01	131480
2007-10-01	143783
2008-01-01	165401
2008-04-01	177506
2008-07-01	167622
2008-10-01	164634
2009-01-01	163975
2009-04-01	175122
2009-07-01	184455
2009-10-01	182814
2010-01-01	184892
2010-04-01	182156
2010-07-01	200884
2010-10-01	200271
2011-01-01	225985
2011-04-01	234709
2011-07-01	231587
2011-10-01	238229
2012-01-01	259929
2012-04-01	264761
2012-07-01	272429
2012-10-01	272884
2013-01-01	265052
2013-04-01	272495
2013-07-01	280377
2013-10-01	291078
2014-01-01	293344
2014-04-01	285593
2014-07-01	274131
2014-10-01	268513
2015-01-01	258737
2015-04-01	256722
2015-07-01	255809
2015-10-01	246696
2016-01-01	252642
2016-04-01	249899
2016-07-01	253829
2016-10-01	233657
2017-01-01	246632
2017-04-01	246516
2017-07-01	246696
2017-10-01	248395
2018-01-01	253121
2018-04-01	242385