Quarter	Millions of US Dollars
1971-01-01	31
1971-07-01	31
1972-04-01	32
1975-04-01	21
1976-04-01	39
1977-04-01	42
1978-07-01	49
1979-07-01	84
1980-04-01	29
1981-07-01	49
1982-04-01	50
1982-10-01	47
1983-04-01	7
1983-07-01	46
1984-07-01	50
1984-10-01	71
1985-07-01	44
1985-10-01	85
1986-01-01	-6
1986-07-01	-35
1986-10-01	260
1987-01-01	165
1987-04-01	-14
1987-07-01	11
1987-10-01	193
1988-01-01	200
1988-04-01	73
1988-07-01	444
1988-10-01	240
1989-04-01	199
1989-07-01	290
1989-10-01	154
1990-01-01	-3
1990-04-01	-7
1990-07-01	259
1990-10-01	272
1991-04-01	-3
1991-07-01	286
1991-10-01	261
1992-04-01	-60
1992-07-01	328
1992-10-01	169
1993-01-01	-200
1993-04-01	-143
1993-07-01	215
1994-04-01	-200
1994-07-01	60
1994-10-01	379
1995-07-01	75
1995-10-01	43
1996-01-01	450
1996-10-01	94
1997-01-01	-170
1997-07-01	306
1997-10-01	-70
1998-07-01	-170
1998-10-01	-249
1999-01-01	244
1999-07-01	-150
1999-10-01	-6
2000-07-01	-150
2000-10-01	-257
2001-01-01	170
2001-07-01	-342
2001-10-01	-200
2002-07-01	-340
2002-10-01	-194
2003-07-01	-430
2003-10-01	-240
2004-07-01	-250
2004-10-01	-473
2005-04-01	372
2005-07-01	-250
2005-10-01	-53
2006-01-01	-450
2006-04-01	445
2006-10-01	-450
2007-07-01	-456
2008-01-01	470
2009-01-01	-295
2009-04-01	520
2009-10-01	-240
2011-01-01	-170
2012-01-01	650
2012-04-01	880
2013-04-01	1000
2014-04-01	1000
2015-04-01	1000
2015-10-01	79
2016-04-01	1000
2017-01-01	-650
2017-04-01	-380
2018-04-01	-500