Quarter	Millions of US Dollars
1996-10-01	1200
1997-01-01	1200
1997-04-01	1200
1997-07-01	1200
1997-10-01	1200
1998-01-01	1200
1998-04-01	1200
1998-07-01	1200
1998-10-01	1200
1999-01-01	1200
1999-04-01	2200
1999-07-01	2200
1999-10-01	2200
2000-01-01	2200
2000-04-01	3600
2000-07-01	3600
2000-10-01	3600
2001-01-01	3600
2001-04-01	3600
2001-07-01	3600
2001-10-01	3600
2002-01-01	3527
2002-04-01	3527
2002-07-01	3491
2002-10-01	3491
2003-01-01	3455
2003-04-01	3455
2003-07-01	3455
2003-10-01	4155
2004-01-01	4747
2004-04-01	4747
2004-07-01	4710
2004-10-01	4710
2005-01-01	4674
2005-04-01	4674
2005-07-01	6888
2005-10-01	6888
2006-01-01	6851
2006-04-01	8001
2006-07-01	9515
2006-10-01	11005
2007-01-01	11005
2007-04-01	11005
2007-07-01	11305
2007-10-01	11305
2008-01-01	11305
2008-04-01	11305
2008-07-01	11305
2008-10-01	11305
2009-01-01	11305
2009-04-01	13305
2009-07-01	14790
2009-10-01	21790
2010-01-01	21710
2010-04-01	22259
2010-07-01	25679
2010-10-01	25675
2011-01-01	25595
2011-04-01	24945
2011-07-01	24865
2011-10-01	29365
2012-01-01	28285
2012-04-01	28285
2012-07-01	32500
2012-10-01	33842
2013-01-01	34756
2013-04-01	34889
2013-07-01	35581
2013-10-01	36211
2014-01-01	36233
2014-04-01	34301
2014-07-01	32906
2014-10-01	33393
2015-01-01	30364
2015-04-01	29718
2015-07-01	29006
2015-10-01	27859
2016-01-01	28019
2016-04-01	37466
2016-07-01	36862
2016-10-01	36346
2017-01-01	34420
2017-04-01	34637
2017-07-01	34369
2017-10-01	33049
2018-01-01	30941
2018-04-01	43081