Quarter	Millions of US Dollars
1982-10-01	13
1983-01-01	13
1983-04-01	13
1983-07-01	13
1983-10-01	13
1984-01-01	13
1984-04-01	13
1984-07-01	12
1984-10-01	12
1985-01-01	12
1985-04-01	12
1985-07-01	14
1985-10-01	15
1986-01-01	17
1986-04-01	18
1986-07-01	19
1986-10-01	19
1987-01-01	21
1987-04-01	20
1987-07-01	21
1987-10-01	25
1988-01-01	24
1988-04-01	22
1988-07-01	22
1988-10-01	24
1989-01-01	23
1989-04-01	21
1989-07-01	22
1989-10-01	21
1990-01-01	19
1990-04-01	20
1990-07-01	22
1990-10-01	22
1991-01-01	21
1991-04-01	22
1991-07-01	23
1991-10-01	24
1992-01-01	23
1992-04-01	24
1992-07-01	25
1997-04-01	50
1997-07-01	50
1997-10-01	50
1998-01-01	50
1998-04-01	50
1998-07-01	50
1998-10-01	50
1999-01-01	50
1999-04-01	50
1999-07-01	50
1999-10-01	50
2000-01-01	50
2002-07-01	350
2002-10-01	350
2003-01-01	350
2003-04-01	350
2003-07-01	350
2003-10-01	350
2004-01-01	350
2004-04-01	350
2004-07-01	350
2004-10-01	350
2005-01-01	350
2005-04-01	350
2005-07-01	350
2005-10-01	350
2006-01-01	350
2006-04-01	350
2006-07-01	350
2006-10-01	350
2007-01-01	350
2007-04-01	350
2007-07-01	350
2007-10-01	850
2008-01-01	850
2008-04-01	850
2008-07-01	850
2008-10-01	850
2009-01-01	850
2009-04-01	850
2009-07-01	850
2009-10-01	1350
2010-01-01	1350
2010-04-01	1350
2010-07-01	1350
2010-10-01	2350
2011-01-01	2350
2011-04-01	2350
2011-07-01	3350
2011-10-01	3350
2012-01-01	3350
2012-04-01	3350
2012-07-01	4350
2012-10-01	3850
2013-01-01	3850
2013-04-01	3850
2013-07-01	3850
2013-10-01	3850
2014-01-01	4850
2014-04-01	5350
2014-07-01	5350
2014-10-01	5350
2015-01-01	4850
2015-04-01	5500
2015-07-01	5500
2015-10-01	7000
2016-01-01	7000
2016-04-01	7000
2016-07-01	8500
2016-10-01	8500
2017-01-01	8500
2017-04-01	10000
2017-07-01	10000
2017-10-01	10000
2018-01-01	10000
2018-04-01	13750