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	98
1978-01-01	127
1978-04-01	154
1978-07-01	134
1978-10-01	82
1979-01-01	122
1979-04-01	259
1979-07-01	343
1979-10-01	474
1980-01-01	399
1980-04-01	264
1980-07-01	193
1980-10-01	57
1981-01-01	38
1981-04-01	33
1981-07-01	167
1981-10-01	157
1982-01-01	159
1982-04-01	162
1982-07-01	117
1982-10-01	187
1983-01-01	230
1983-04-01	270
1983-07-01	205
1983-10-01	217
1984-01-01	213
1984-04-01	176
1984-07-01	176
1984-10-01	503
1985-01-01	547
1985-04-01	543
1985-07-01	599
1985-10-01	249
1986-01-01	251
1986-04-01	249
1986-07-01	268
1986-10-01	297
1987-01-01	319
1987-04-01	458
1987-07-01	477
1987-10-01	411
1988-01-01	356
1988-04-01	325
1988-07-01	262
1988-10-01	258
1989-01-01	211
1989-04-01	503
1989-07-01	680
1989-10-01	800
1990-01-01	887
1990-04-01	459
1990-07-01	436
1990-10-01	332
1991-01-01	228
1991-04-01	294
1991-07-01	202
1991-10-01	335
1992-01-01	281
1992-04-01	410
1992-07-01	369
1992-10-01	217
1993-01-01	217
1993-04-01	0
1993-07-01	3
1993-10-01	3
1994-01-01	3
1994-04-01	3
1994-07-01	26
1994-10-01	26
1995-01-01	32
1995-04-01	32
1995-07-01	108
1995-10-01	108
1996-01-01	108
1996-04-01	383
1996-07-01	277
1996-10-01	273
1997-01-01	252
1997-04-01	2
1997-07-01	17
1997-10-01	17
1998-01-01	17
1998-04-01	17
1998-07-01	2
1998-10-01	376
1999-01-01	403
1999-04-01	391
1999-07-01	452
1999-10-01	290
2000-01-01	251
2000-04-01	579
2000-07-01	522
2000-10-01	319
2001-01-01	352
2001-04-01	92
2001-07-01	376
2001-10-01	648
2002-01-01	610
2002-04-01	622
2002-07-01	334
2002-10-01	36
2003-01-01	108
2003-04-01	183
2003-07-01	304
2003-10-01	304
2004-01-01	583
2004-04-01	1240
2004-07-01	1489
2004-10-01	1822
2005-01-01	1426
2005-04-01	635
2005-07-01	314
2005-10-01	423
2006-01-01	583
2006-04-01	587
2006-07-01	984
2006-10-01	888
2007-01-01	762
2007-04-01	1029
2007-07-01	1218
2007-10-01	1030
2008-01-01	1752
2008-04-01	1668
2008-07-01	1717
2008-10-01	2313
2009-01-01	1762
2009-04-01	1608
2009-07-01	990
2009-10-01	576
2010-01-01	1195
2010-04-01	3396
2010-07-01	3487
2010-10-01	3281
2011-01-01	2750
2011-04-01	1927
2011-07-01	2707
2011-10-01	5874
2012-01-01	9510
2012-04-01	9865
2012-07-01	11415
2012-10-01	13383
2013-01-01	6952
2013-04-01	8751
2013-07-01	10146
2013-10-01	7507
2014-01-01	7453
2014-04-01	4427
2014-07-01	1576
2014-10-01	1578
2015-01-01	3097
2015-04-01	4536
2015-07-01	4666
2015-10-01	7679
2016-01-01	8312
2016-04-01	6697
2016-07-01	6001
2016-10-01	4367
2017-01-01	6536
2017-04-01	7510
2017-07-01	8455
2017-10-01	7206
2018-01-01	4862
2018-04-01	5715