Quarter	Millions of US Dollars
1971-01-01	0
1971-04-01	0
1971-07-01	0
1971-10-01	0
1972-01-01	0
1972-04-01	0
1972-07-01	0
1972-10-01	0
1973-01-01	0
1973-04-01	0
1973-07-01	0
1973-10-01	0
1974-01-01	0
1974-04-01	0
1974-07-01	0
1974-10-01	0
1975-01-01	0
1975-04-01	0
1975-07-01	0
1975-10-01	0
1976-01-01	0
1976-04-01	0
1976-07-01	0
1976-10-01	0
1977-01-01	0
1977-04-01	0
1977-07-01	30
1977-10-01	85
1978-01-01	114
1978-04-01	157
1978-07-01	140
1978-10-01	125
1979-01-01	165
1979-04-01	317
1979-07-01	413
1979-10-01	543
1980-01-01	503
1980-04-01	419
1980-07-01	365
1980-10-01	232
1981-01-01	245
1981-04-01	248
1981-07-01	432
1981-10-01	418
1982-01-01	390
1982-04-01	418
1982-07-01	319
1982-10-01	532
1983-01-01	691
1983-04-01	692
1983-07-01	679
1983-10-01	570
1984-01-01	468
1984-04-01	569
1984-07-01	641
1984-10-01	1579
1985-01-01	1682
1985-04-01	1547
1985-07-01	1616
1985-10-01	754
1986-01-01	758
1986-04-01	883
1986-07-01	1071
1986-10-01	1308
1987-01-01	1431
1987-04-01	1565
1987-07-01	1418
1987-10-01	1289
1988-01-01	1239
1988-04-01	1317
1988-07-01	1180
1988-10-01	1003
1989-01-01	843
1989-04-01	1047
1989-07-01	1364
1989-10-01	1726
1990-01-01	1846
1990-04-01	1313
1990-07-01	1111
1990-10-01	862
1991-01-01	584
1991-04-01	504
1991-07-01	571
1991-10-01	766
1992-01-01	695
1992-04-01	1355
1992-07-01	1331
1992-10-01	970
1993-01-01	1018
1993-04-01	646
1993-07-01	767
1993-10-01	933
1994-01-01	892
1994-04-01	765
1994-07-01	893
1994-10-01	928
1995-01-01	991
1995-04-01	669
1995-07-01	622
1995-10-01	776
1996-01-01	1095
1996-04-01	1383
1996-07-01	1015
1996-10-01	975
1997-01-01	868
1997-04-01	693
1997-07-01	741
1997-10-01	769
1998-01-01	804
1998-04-01	1035
1998-07-01	959
1998-10-01	1717
1999-01-01	1912
1999-04-01	2225
1999-07-01	2625
1999-10-01	1659
2000-01-01	1533
2000-04-01	1516
2000-07-01	1485
2000-10-01	1922
2001-01-01	1977
2001-04-01	1734
2001-07-01	2427
2001-10-01	3150
2002-01-01	2717
2002-04-01	2884
2002-07-01	1834
2002-10-01	2826
2003-01-01	3577
2003-04-01	4279
2003-07-01	4696
2003-10-01	4730
2004-01-01	5717
2004-04-01	5696
2004-07-01	6764
2004-10-01	5846
2005-01-01	5341
2005-04-01	6036
2005-07-01	6827
2005-10-01	9369
2006-01-01	11263
2006-04-01	9524
2006-07-01	12543
2006-10-01	12552
2007-01-01	17844
2007-04-01	19131
2007-07-01	17671
2007-10-01	17313
2008-01-01	17743
2008-04-01	18579
2008-07-01	17674
2008-10-01	18871
2009-01-01	17043
2009-04-01	18860
2009-07-01	19637
2009-10-01	16344
2010-01-01	14999
2010-04-01	19452
2010-07-01	22980
2010-10-01	20753
2011-01-01	23461
2011-04-01	22508
2011-07-01	24892
2011-10-01	28475
2012-01-01	29706
2012-04-01	28222
2012-07-01	26460
2012-10-01	31152
2013-01-01	26871
2013-04-01	36312
2013-07-01	40022
2013-10-01	45224
2014-01-01	50127
2014-04-01	39125
2014-07-01	39364
2014-10-01	41007
2015-01-01	37410
2015-04-01	49101
2015-07-01	50197
2015-10-01	50132
2016-01-01	62373
2016-04-01	58830
2016-07-01	60386
2016-10-01	59754
2017-01-01	64536
2017-04-01	63398
2017-07-01	51801
2017-10-01	47790
2018-01-01	37509
2018-04-01	47353