Quarter	Millions of US Dollars
1997-01-01	0
1997-04-01	0
1997-07-01	0
1997-10-01	0
1998-01-01	0
1998-04-01	0
1998-07-01	0
1998-10-01	0
1999-01-01	0
1999-04-01	0
1999-07-01	0
1999-10-01	0
2000-01-01	0
2000-04-01	0
2000-07-01	0
2000-10-01	0
2001-01-01	3
2001-04-01	3
2001-07-01	7
2001-10-01	7
2002-01-01	8
2002-04-01	8
2002-07-01	9
2002-10-01	9
2003-01-01	9
2003-04-01	9
2003-07-01	9
2003-10-01	9
2004-01-01	9
2004-04-01	9
2004-07-01	9
2004-10-01	9
2005-01-01	11
2005-04-01	11
2005-07-01	14
2005-10-01	14
2006-01-01	14
2006-04-01	14
2006-07-01	14
2006-10-01	14
2007-01-01	17
2007-04-01	17
2007-07-01	21
2007-10-01	21
2008-01-01	26
2008-04-01	26
2008-07-01	32
2008-10-01	32
2009-01-01	32
2009-04-01	32
2009-07-01	32
2009-10-01	32
2010-01-01	37
2010-04-01	37
2010-07-01	41
2010-10-01	41
2011-01-01	41
2011-04-01	41
2011-07-01	41
2011-10-01	41
2012-01-01	254
2012-04-01	241
2012-07-01	226
2012-10-01	231
2013-01-01	0
2013-04-01	0
2013-07-01	0
2013-10-01	0
2014-01-01	0
2014-04-01	0
2014-07-01	0
2014-10-01	182
2015-01-01	161
2015-04-01	168
2015-07-01	168
2015-10-01	0
2016-01-01	0
2016-04-01	0
2016-07-01	0
2016-10-01	0
2017-01-01	0
2017-04-01	0
2017-07-01	0
2017-10-01	0
2018-01-01	0
2018-04-01	0