Quarter	Millions of US Dollars
1993-07-01	60
1993-10-01	60
1994-01-01	60
1994-04-01	60
1994-07-01	60
1994-10-01	60
1995-01-01	60
1995-04-01	60
1995-07-01	60
1995-10-01	60
1996-01-01	60
1996-04-01	60
1996-07-01	48
1996-10-01	48
1997-01-01	36
1997-04-01	36
1997-07-01	186
1997-10-01	174
1998-01-01	162
1998-04-01	162
1998-07-01	150
1998-10-01	150
1999-01-01	150
1999-04-01	150
1999-07-01	150
1999-10-01	150
2000-01-01	150
2000-04-01	150
2000-07-01	150
2000-10-01	150
2001-01-01	150
2001-04-01	150
2001-07-01	150
2001-10-01	475
2002-01-01	475
2002-04-01	475
2002-07-01	475
2002-10-01	475
2003-01-01	475
2003-04-01	475
2003-07-01	775
2003-10-01	775
2004-01-01	775
2004-04-01	775
2004-07-01	775
2004-10-01	1205
2005-01-01	1205
2005-04-01	1205
2005-07-01	1205
2005-10-01	1205
2006-01-01	1205
2006-04-01	1205
2006-07-01	1205
2006-10-01	1205
2007-01-01	1205
2007-04-01	1205
2007-07-01	1055
2007-10-01	1055
2008-01-01	1055
2008-04-01	1055
2008-07-01	1055
2008-10-01	1055
2009-01-01	1055
2009-04-01	1055
2009-07-01	1055
2009-10-01	1055
2010-01-01	1055
2010-04-01	1055
2010-07-01	1055
2010-10-01	1055
2011-01-01	1055
2011-04-01	1055
2011-07-01	1055
2011-10-01	730
2012-01-01	930
2012-04-01	1630
2012-07-01	1630
2012-10-01	1630
2013-01-01	2330
2013-04-01	2430
2013-07-01	2130
2013-10-01	2630
2014-01-01	2630
2014-04-01	2930
2014-07-01	2930
2014-10-01	2830
2015-01-01	2830
2015-04-01	2830
2015-07-01	2830
2015-10-01	2830
2016-01-01	2830
2016-04-01	3530
2016-07-01	3530
2016-10-01	3530
2017-01-01	3230
2017-04-01	3730
2017-07-01	3730
2017-10-01	3730
2018-01-01	3730
2018-04-01	3730