Quarter	Millions of US Dollars
2007-01-01	200
2007-04-01	200
2007-07-01	200
2007-10-01	200
2008-01-01	200
2008-04-01	700
2008-07-01	700
2008-10-01	700
2009-01-01	700
2009-04-01	700
2009-07-01	700
2009-10-01	700
2010-01-01	700
2010-04-01	700
2010-07-01	950
2010-10-01	950
2011-01-01	950
2011-04-01	950
2011-07-01	950
2011-10-01	950
2012-01-01	750
2012-04-01	1000
2012-07-01	2000
2012-10-01	2000
2013-01-01	2000
2013-04-01	2000
2013-07-01	2000
2013-10-01	2150
2014-01-01	2150
2014-04-01	2150
2014-07-01	2150
2014-10-01	2150
2015-01-01	2150
2015-04-01	2150
2015-07-01	1900
2015-10-01	1900
2016-01-01	1900
2016-04-01	2150
2016-07-01	2700
2016-10-01	2700
2017-01-01	2700
2017-04-01	3307
2017-07-01	2821
2017-10-01	2819
2018-01-01	2861
2018-04-01	2815