Quarter	Millions of US Dollars
1997-01-01	12290
1997-04-01	12656
1997-07-01	12903
1997-10-01	13117
1998-01-01	13349
1998-04-01	13584
1998-07-01	12575
1998-10-01	12578
1999-01-01	12578
1999-04-01	12737
1999-07-01	12922
1999-10-01	13115
2000-01-01	13292
2000-04-01	13497
2000-07-01	13708
2000-10-01	13924
2001-01-01	14122
2001-04-01	14298
2001-07-01	14450
2001-10-01	14587
2002-01-01	14704
2002-04-01	14834
2002-07-01	14944
2002-10-01	15064
2003-01-01	15155
2003-04-01	15263
2003-07-01	15451
2003-10-01	15477
2004-01-01	15479
2004-04-01	15544
2004-07-01	18198
2004-10-01	18338
2005-01-01	18364
2005-04-01	18564
2005-07-01	18736
2005-10-01	18913
2006-01-01	19047
2006-04-01	19210
2006-07-01	18977
2006-10-01	19189
2007-01-01	19251
2007-04-01	19434
2007-07-01	19708
2007-10-01	19760
2008-01-01	20647
2008-04-01	20740
2008-07-01	20555
2008-10-01	22237
2009-01-01	30139
2009-04-01	39111
2009-07-01	55190
2009-10-01	71026
2010-01-01	81818
2010-04-01	87153
2010-07-01	87979
2010-10-01	88563
2011-01-01	88987
2011-04-01	89391
2011-07-01	90931
2011-10-01	91996
2012-01-01	92290
2012-04-01	94323
2012-07-01	94409
2012-10-01	94906
2013-01-01	101794
2013-04-01	108889
2013-07-01	109456
2013-10-01	109926
2014-01-01	110424
2014-04-01	110983
2014-07-01	111361
2014-10-01	110668
2015-01-01	111747
2015-04-01	111275
2015-07-01	115275
2015-10-01	121845
2016-01-01	125658
2016-04-01	132742
2016-07-01	139839
2016-10-01	139437
2017-01-01	140600
2017-04-01	141105
2017-07-01	146063
2017-10-01	150775
2018-01-01	149571