Quarter	Millions of US Dollars
1972-10-01	30
1973-01-01	23
1973-04-01	20
1973-07-01	21
1974-01-01	23
1980-01-01	30
1980-07-01	-49
1982-10-01	20
1983-01-01	-34
1983-04-01	12
1985-10-01	23
1986-01-01	-13
1988-01-01	81
1988-04-01	-31
1989-01-01	-26
1990-10-01	37
1991-07-01	16
1992-10-01	-107
1993-04-01	-9
1993-10-01	-33
1995-01-01	-89
1995-04-01	96
1995-07-01	-63
1995-10-01	-31
1996-07-01	-19
1996-10-01	181
1997-01-01	303
1997-10-01	325
1998-01-01	55
1998-04-01	65
1998-07-01	31
1998-10-01	540
1999-01-01	-96
1999-04-01	217
1999-07-01	738
1999-10-01	-8
2000-01-01	994
2000-04-01	-730
2000-07-01	38
2000-10-01	-76
2001-01-01	1530
2001-04-01	485
2001-07-01	372
2001-10-01	-292
2002-01-01	170
2002-04-01	-44
2002-07-01	-227
2002-10-01	-1169
2003-01-01	654
2003-04-01	898
2003-07-01	331
2003-10-01	-249
2004-01-01	946
2004-04-01	-372
2004-07-01	787
2004-10-01	-53
2005-01-01	831
2005-04-01	977
2005-07-01	-646
2005-10-01	318
2006-01-01	385
2006-04-01	-1507
2006-07-01	592
2006-10-01	829
2007-01-01	2183
2007-04-01	-1267
2007-07-01	-3159
2007-10-01	-322
2008-01-01	3390
2008-04-01	539
2008-07-01	846
2008-10-01	3935
2009-01-01	-887
2009-04-01	1023
2009-07-01	-203
2009-10-01	-363
2010-01-01	-1035
2010-04-01	-887
2010-07-01	-2321
2010-10-01	3027
2011-01-01	-19
2011-04-01	3278
2011-07-01	-2257
2011-10-01	-961
2012-01-01	1208
2012-04-01	-2992
2012-07-01	986
2012-10-01	1356
2013-01-01	1095
2013-04-01	-359
2013-07-01	-146
2013-10-01	-29
2014-01-01	1767
2014-04-01	169
2014-07-01	-812
2014-10-01	166
2015-01-01	1389
2015-04-01	619
2015-07-01	-362
2015-10-01	-357
2016-01-01	859
2016-04-01	-1351
2016-07-01	-11
2016-10-01	455
2017-01-01	-249
2017-04-01	-192
2017-07-01	634
2017-10-01	-907
2018-01-01	218
2018-04-01	736