Quarter	Millions of US Dollars
1971-01-01	88
1971-04-01	141
1971-07-01	169
1971-10-01	221
1972-01-01	395
1972-04-01	474
1972-07-01	589
1972-10-01	809
1973-01-01	911
1973-04-01	1284
1973-07-01	1342
1973-10-01	1693
1974-01-01	1838
1974-04-01	2256
1974-07-01	2305
1974-10-01	2442
1975-01-01	2565
1975-04-01	2891
1975-07-01	2930
1975-10-01	3055
1976-01-01	3177
1976-04-01	3369
1976-07-01	3492
1976-10-01	3754
1977-01-01	3956
1977-04-01	4175
1977-07-01	4340
1977-10-01	4715
1978-01-01	5182
1978-04-01	5632
1978-07-01	6149
1978-10-01	6642
1979-01-01	6733
1979-04-01	6929
1979-07-01	7174
1979-10-01	7129
1980-01-01	6816
1980-04-01	7050
1980-07-01	7102
1980-10-01	6836
1981-01-01	6695
1981-04-01	6385
1981-07-01	6435
1981-10-01	6498
1982-01-01	6327
1982-04-01	6294
1982-07-01	6179
1982-10-01	6415
1983-01-01	6483
1983-04-01	6443
1983-07-01	6378
1983-10-01	6284
1984-01-01	6399
1984-04-01	6476
1984-07-01	6437
1984-10-01	6679
1985-01-01	6787
1985-04-01	7510
1985-07-01	7875
1985-10-01	7002
1986-01-01	6963
1986-04-01	7052
1986-07-01	7335
1986-10-01	7236
1987-01-01	7408
1987-04-01	7146
1987-07-01	6831
1987-10-01	6846
1988-01-01	6565
1988-04-01	6088
1988-07-01	5876
1988-10-01	6172
1989-01-01	5741
1989-04-01	5280
1989-07-01	5371
1989-10-01	5517
1990-01-01	5320
1990-04-01	4544
1990-07-01	4320
1990-10-01	4037
1991-01-01	3534
1991-04-01	4347
1991-07-01	4369
1991-10-01	4704
1992-01-01	7022
1992-04-01	7762
1992-07-01	8074
1992-10-01	7464
1993-01-01	7783
1993-04-01	5827
1993-07-01	7215
1993-10-01	7810
1994-01-01	8646
1994-04-01	8310
1994-07-01	8322
1994-10-01	8968
1995-01-01	9652
1995-04-01	9843
1995-07-01	9899
1995-10-01	10339
1996-01-01	10421
1996-04-01	10478
1996-07-01	10808
1996-10-01	13075
1997-01-01	12809
1997-04-01	13608
1997-07-01	14563
1997-10-01	14684
1998-01-01	16406
1998-04-01	16659
1998-07-01	17129
1998-10-01	17558
1999-01-01	18013
1999-04-01	20743
1999-07-01	21348
1999-10-01	21357
2000-01-01	22494
2000-04-01	24222
2000-07-01	24741
2000-10-01	24625
2001-01-01	24728
2001-04-01	25513
2001-07-01	27637
2001-10-01	27056
2002-01-01	27644
2002-04-01	30155
2002-07-01	30669
2002-10-01	30859
2003-01-01	31485
2003-04-01	33995
2003-07-01	34932
2003-10-01	35895
2004-01-01	38123
2004-04-01	40474
2004-07-01	40296
2004-10-01	43795
2005-01-01	44259
2005-04-01	46660
2005-07-01	51593
2005-10-01	54889
2006-01-01	65759
2006-04-01	71572
2006-07-01	74590
2006-10-01	90049
2007-01-01	95078
2007-04-01	104339
2007-07-01	110483
2007-10-01	116466
2008-01-01	118624
2008-04-01	125785
2008-07-01	124148
2008-10-01	118767
2009-01-01	116817
2009-04-01	127221
2009-07-01	137730
2009-10-01	139635
2010-01-01	140894
2010-04-01	141100
2010-07-01	148657
2010-10-01	153690
2011-01-01	160850
2011-04-01	159162
2011-07-01	155932
2011-10-01	167690
2012-01-01	172993
2012-04-01	170262
2012-07-01	176955
2012-10-01	190478
2013-01-01	194254
2013-04-01	196413
2013-07-01	203316
2013-10-01	209221
2014-01-01	212939
2014-04-01	224976
2014-07-01	227351
2014-10-01	234357
2015-01-01	236497
2015-04-01	250693
2015-07-01	251382
2015-10-01	257948
2016-01-01	261371
2016-04-01	285207
2016-07-01	290132
2016-10-01	331792
2017-01-01	351153
2017-04-01	377475
2017-07-01	385176
2017-10-01	415204
2018-01-01	435889
2018-04-01	473292