Quarter	Millions of US Dollars
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	0
1977-10-01	0
1978-01-01	28
1978-04-01	54
1978-07-01	61
1978-10-01	61
1979-01-01	30
1979-04-01	25
1979-07-01	25
1979-10-01	25
1980-01-01	55
1980-04-01	30
1980-07-01	30
1980-10-01	30
1981-01-01	15
1981-04-01	71
1981-07-01	71
1981-10-01	72
1982-01-01	56
1982-04-01	10
1982-07-01	92
1982-10-01	134
1983-01-01	133
1983-04-01	121
1983-07-01	83
1983-10-01	43
1984-01-01	73
1984-04-01	94
1984-07-01	51
1984-10-01	236
1985-01-01	255
1985-04-01	320
1985-07-01	401
1985-10-01	311
1986-01-01	274
1986-04-01	219
1986-07-01	265
1986-10-01	185
1987-01-01	321
1987-04-01	325
1987-07-01	361
1987-10-01	384
1988-01-01	233
1988-04-01	247
1988-07-01	362
1988-10-01	527
1989-01-01	770
1989-04-01	884
1989-07-01	656
1989-10-01	430
1990-01-01	280
1990-04-01	264
1990-07-01	502
1990-10-01	673
1991-01-01	689
1991-04-01	770
1991-07-01	1102
1991-10-01	1368
1992-01-01	1380
1992-04-01	1312
1992-07-01	1033
1992-10-01	859
1993-01-01	833
1993-04-01	1051
1993-07-01	3650
1993-10-01	3594
1994-01-01	3940
1994-04-01	3407
1994-07-01	3373
1994-10-01	2980
1995-01-01	3560
1995-04-01	3702
1995-07-01	3610
1995-10-01	3773
1996-01-01	3495
1996-04-01	2656
1996-07-01	1500
1996-10-01	2926
1997-01-01	3116
1997-04-01	3526
1997-07-01	3528
1997-10-01	3266
1998-01-01	3852
1998-04-01	3231
1998-07-01	2735
1998-10-01	2491
1999-01-01	3263
1999-04-01	2426
1999-07-01	2566
1999-10-01	2544
2000-01-01	1924
2000-04-01	1598
2000-07-01	1677
2000-10-01	1339
2001-01-01	1335
2001-04-01	1859
2001-07-01	1678
2001-10-01	1645
2002-01-01	1571
2002-04-01	2025
2002-07-01	2372
2002-10-01	2025
2003-01-01	2057
2003-04-01	1708
2003-07-01	1258
2003-10-01	1200
2004-01-01	1350
2004-04-01	2733
2004-07-01	3080
2004-10-01	4171
2005-01-01	4305
2005-04-01	3031
2005-07-01	3201
2005-10-01	2123
2006-01-01	1771
2006-04-01	1833
2006-07-01	2332
2006-10-01	1961
2007-01-01	3211
2007-04-01	4573
2007-07-01	3851
2007-10-01	3904
2008-01-01	2691
2008-04-01	1680
2008-07-01	2316
2008-10-01	1896
2009-01-01	2133
2009-04-01	2131
2009-07-01	2166
2009-10-01	2114
2010-01-01	2466
2010-04-01	3332
2010-07-01	4079
2010-10-01	4254
2011-01-01	3299
2011-04-01	2761
2011-07-01	3194
2011-10-01	3720
2012-01-01	4268
2012-04-01	4375
2012-07-01	3879
2012-10-01	3849
2013-01-01	2843
2013-04-01	2032
2013-07-01	3360
2013-10-01	4558
2014-01-01	4910
2014-04-01	4704
2014-07-01	5401
2014-10-01	5150
2015-01-01	5339
2015-04-01	6791
2015-07-01	5498
2015-10-01	5430
2016-01-01	8154
2016-04-01	7447
2016-07-01	6930
2016-10-01	6692
2017-01-01	6964
2017-04-01	8540
2017-07-01	8013
2017-10-01	7228
2018-01-01	5388
2018-04-01	5245