Quarter	Millions of US Dollars
1973-10-01	2
1974-01-01	3
1974-04-01	3
1974-07-01	3
1974-10-01	3
1975-01-01	3
1975-04-01	3
1975-07-01	3
1975-10-01	3
1976-01-01	3
1976-04-01	3
1976-07-01	3
1976-10-01	3
1977-01-01	3
1977-04-01	3
1977-07-01	3
1977-10-01	4
1978-01-01	4
1978-04-01	4
1978-07-01	5
1978-10-01	5
1979-01-01	5
1979-04-01	5
1979-07-01	5
1979-10-01	5
1980-01-01	4
1980-04-01	35
1980-07-01	35
1980-10-01	35
1981-01-01	34
1981-04-01	54
1981-07-01	54
1981-10-01	191
1982-01-01	189
1982-04-01	218
1982-07-01	217
1982-10-01	218
1983-01-01	217
1983-04-01	216
1983-07-01	217
1983-10-01	216
1984-01-01	216
1984-04-01	216
1984-07-01	234
1984-10-01	271
1985-01-01	422
1985-04-01	422
1985-07-01	460
1985-10-01	640
1986-01-01	976
1986-04-01	1014
1986-07-01	1044
1986-10-01	1077
1987-01-01	1524
1987-04-01	1525
1987-07-01	1476
1987-10-01	1815
1988-01-01	1786
1988-04-01	1855
1988-07-01	2126
1988-10-01	2240
1989-01-01	2186
1989-04-01	2385
1989-07-01	2429
1989-10-01	2678
1990-01-01	2790
1990-04-01	2830
1990-07-01	3075
1990-10-01	3327
1991-01-01	3568
1991-04-01	3557
1991-07-01	3864
1991-10-01	4279
1992-01-01	3865
1992-04-01	4450
1992-07-01	4663
1992-10-01	4140
1993-01-01	3966
1993-04-01	3925
1993-07-01	2828
1993-10-01	2973
1994-01-01	3278
1994-04-01	3499
1994-07-01	3815
1994-10-01	3361
1995-01-01	3635
1995-04-01	3670
1995-07-01	3656
1995-10-01	3733
1996-01-01	3997
1996-04-01	4015
1996-07-01	4447
1996-10-01	4510
1997-01-01	4712
1997-04-01	5212
1997-07-01	6059
1997-10-01	6083
1998-01-01	6057
1998-04-01	5907
1998-07-01	5734
1998-10-01	5855
1999-01-01	5852
1999-04-01	5427
1999-07-01	5302
1999-10-01	4903
2000-01-01	4573
2000-04-01	4449
2000-07-01	4431
2000-10-01	4429
2001-01-01	4220
2001-04-01	4104
2001-07-01	3973
2001-10-01	3966
2002-01-01	3812
2002-04-01	3942
2002-07-01	3553
2002-10-01	3492
2003-01-01	3272
2003-04-01	3277
2003-07-01	3381
2003-10-01	3489
2004-01-01	4290
2004-04-01	4789
2004-07-01	5061
2004-10-01	5923
2005-01-01	6665
2005-04-01	7176
2005-07-01	8367
2005-10-01	9026
2006-01-01	11771
2006-04-01	14046
2006-07-01	14825
2006-10-01	16214
2007-01-01	20975
2007-04-01	23050
2007-07-01	24787
2007-10-01	27894
2008-01-01	28473
2008-04-01	28516
2008-07-01	28309
2008-10-01	29166
2009-01-01	28266
2009-04-01	27597
2009-07-01	28333
2009-10-01	30467
2010-01-01	30149
2010-04-01	30009
2010-07-01	29001
2010-10-01	28461
2011-01-01	27538
2011-04-01	26403
2011-07-01	27641
2011-10-01	26073
2012-01-01	23077
2012-04-01	20856
2012-07-01	19453
2012-10-01	19442
2013-01-01	20511
2013-04-01	21773
2013-07-01	22815
2013-10-01	22773
2014-01-01	23426
2014-04-01	25376
2014-07-01	27674
2014-10-01	27192
2015-01-01	28117
2015-04-01	30679
2015-07-01	31372
2015-10-01	31143
2016-01-01	30987
2016-04-01	30323
2016-07-01	33996
2016-10-01	34778
2017-01-01	36855
2017-04-01	38236
2017-07-01	39273
2017-10-01	41975
2018-01-01	44154
2018-04-01	42759