Quarter	Millions of US Dollars
1997-01-01	4871
1997-04-01	4871
1997-07-01	4871
1997-10-01	4871
1998-01-01	4871
1998-04-01	4871
1998-07-01	4871
1998-10-01	4130
1999-01-01	4130
1999-04-01	4130
1999-07-01	4130
1999-10-01	4130
2000-01-01	4130
2000-04-01	4130
2000-07-01	4130
2000-10-01	4130
2001-01-01	4130
2001-04-01	4130
2001-07-01	4130
2001-10-01	4130
2002-01-01	4870
2002-04-01	4852
2002-07-01	4852
2002-10-01	4434
2003-01-01	5166
2003-04-01	5166
2003-07-01	5129
2003-10-01	4719
2004-01-01	4719
2004-04-01	5219
2004-07-01	5219
2004-10-01	6104
2005-01-01	6395
2005-04-01	6338
2005-07-01	7085
2005-10-01	7569
2006-01-01	7489
2006-04-01	7529
2006-07-01	7525
2006-10-01	7558
2007-01-01	8985
2007-04-01	8895
2007-07-01	9496
2007-10-01	9578
2008-01-01	8352
2008-04-01	8220
2008-07-01	8119
2008-10-01	8011
2009-01-01	8962
2009-04-01	9090
2009-07-01	10192
2009-10-01	10174
2010-01-01	10142
2010-04-01	10659
2010-07-01	10723
2010-10-01	13200
2011-01-01	13230
2011-04-01	13300
2011-07-01	13245
2011-10-01	13320
2012-01-01	14461
2012-04-01	14434
2012-07-01	14555
2012-10-01	14638
2013-01-01	14565
2013-04-01	14290
2013-07-01	14303
2013-10-01	14293
2014-01-01	14275
2014-04-01	14288
2014-07-01	14133
2014-10-01	16883
2015-01-01	17480
2015-04-01	17302
2015-07-01	18457
2015-10-01	19284
2016-01-01	20638
2016-04-01	19429
2016-07-01	19227
2016-10-01	20824
2017-01-01	21123
2017-04-01	21262
2017-07-01	21314
2017-10-01	21412
2018-01-01	21535
2018-04-01	21265