Quarter	Millions of US Dollars
2003-01-01	500
2003-04-01	750
2003-07-01	750
2003-10-01	750
2004-01-01	750
2004-04-01	750
2004-07-01	750
2004-10-01	750
2005-01-01	750
2005-04-01	750
2005-07-01	750
2005-10-01	750
2006-01-01	750
2006-04-01	750
2006-07-01	750
2006-10-01	750
2007-01-01	750
2007-04-01	750
2007-07-01	750
2007-10-01	750
2008-01-01	600
2008-04-01	350
2008-07-01	350
2008-10-01	350
2009-01-01	350
2009-04-01	1100
2009-07-01	1100
2009-10-01	1100
2010-01-01	2350
2010-04-01	3100
2010-07-01	3100
2010-10-01	3100
2011-01-01	3100
2011-04-01	3100
2011-07-01	3100
2011-10-01	3850
2012-01-01	3850
2012-04-01	3850
2012-07-01	5350
2012-10-01	5448
2013-01-01	5097
2013-04-01	5142
2013-07-01	6638
2013-10-01	6637
2014-01-01	6638
2014-04-01	5890
2014-07-01	7137
2014-10-01	7129
2015-01-01	7121
2015-04-01	6369
2015-07-01	6352
2015-10-01	7854
2016-01-01	8466
2016-04-01	8463
2016-07-01	8459
2016-10-01	10450
2017-01-01	11652
2017-04-01	11655
2017-07-01	17307
2017-10-01	17237
2018-01-01	17239
2018-04-01	18200