Quarter	Millions of US Dollars
1979-01-01	48
1979-04-01	46
1979-07-01	45
1979-10-01	42
1980-01-01	40
1980-04-01	46
1980-07-01	103
1980-10-01	100
1981-01-01	95
1981-04-01	86
1981-07-01	86
1981-10-01	90
1982-01-01	82
1982-04-01	80
1982-07-01	77
1982-10-01	85
1983-01-01	83
1983-04-01	81
1983-07-01	80
1983-10-01	80
1984-01-01	83
1984-04-01	78
1984-07-01	74
1984-10-01	72
1985-01-01	72
1985-04-01	73
1985-07-01	83
1985-10-01	90
1986-01-01	99
1986-04-01	107
1986-07-01	65
1986-10-01	63
1987-01-01	68
1987-04-01	68
1987-07-01	68
1987-10-01	82
1988-01-01	81
1988-04-01	75
1988-07-01	74
1988-10-01	80
1989-01-01	75
1989-04-01	70
1989-07-01	72
1989-10-01	70
1990-01-01	63
1990-04-01	66
1990-07-01	72
1990-10-01	74
1991-01-01	320
1991-04-01	320
1991-07-01	320
1991-10-01	320
1992-01-01	320
1992-04-01	320
1992-07-01	320
1992-10-01	320
1993-01-01	320
1993-04-01	320
1993-07-01	320
1993-10-01	320
1994-01-01	320
1994-04-01	320
1994-07-01	320
1994-10-01	320
1995-01-01	320
1995-04-01	320
1995-07-01	320
1995-10-01	320
1999-04-01	500
1999-07-01	500
1999-10-01	500
2000-01-01	500
2000-04-01	500
2000-07-01	500
2000-10-01	500
2001-01-01	500
2001-04-01	500
2001-07-01	500
2001-10-01	1150
2002-01-01	1150
2002-04-01	2049
2002-07-01	2046
2002-10-01	2165
2003-01-01	3177
2003-04-01	3193
2003-07-01	3200
2003-10-01	3229
2004-01-01	3817
2004-04-01	3815
2004-07-01	3822
2004-10-01	3859
2005-01-01	3839
2005-04-01	3813
2005-07-01	3450
2005-10-01	3450
2006-01-01	3450
2006-04-01	3450
2006-07-01	3450
2006-10-01	3450
2007-01-01	3450
2007-04-01	3450
2007-07-01	2850
2007-10-01	2850
2008-01-01	2250
2008-04-01	2250
2008-07-01	2250
2008-10-01	2250
2009-01-01	2250
2009-04-01	1750
2009-07-01	1750
2009-10-01	1750
2010-01-01	1750
2010-04-01	1750
2010-07-01	3311
2010-10-01	3331
2011-01-01	3315
2011-04-01	3328
2011-07-01	4593
2011-10-01	4583
2012-01-01	3887
2012-04-01	3852
2012-07-01	3923
2012-10-01	5408
2013-01-01	4419
2013-04-01	4362
2013-07-01	4364
2013-10-01	4329
2014-01-01	4289
2014-04-01	4289
2014-07-01	4272
2014-10-01	6297
2015-01-01	6164
2015-04-01	7745
2015-07-01	7680
2015-10-01	7608
2016-01-01	10462
2016-04-01	10329
2016-07-01	10352
2016-10-01	10134
2017-01-01	10189
2017-04-01	12774
2017-07-01	12962
2017-10-01	13062
2018-01-01	16231
2018-04-01	15857