Quarter	Millions of US Dollars
1997-01-01	8031
1997-04-01	8661
1997-07-01	9399
1997-10-01	9164
1998-01-01	9223
1998-04-01	8824
1998-07-01	8906
1998-10-01	9711
1999-01-01	11791
1999-04-01	12143
1999-07-01	13184
1999-10-01	14626
2000-01-01	14791
2000-04-01	14153
2000-07-01	15063
2000-10-01	16028
2001-01-01	16103
2001-04-01	19693
2001-07-01	20111
2001-10-01	20489
2002-01-01	22730
2002-04-01	24836
2002-07-01	24070
2002-10-01	24500
2003-01-01	24686
2003-04-01	25229
2003-07-01	25768
2003-10-01	25597
2004-01-01	26094
2004-04-01	26508
2004-07-01	25515
2004-10-01	25630
2005-01-01	25070
2005-04-01	25043
2005-07-01	25576
2005-10-01	25347
2006-01-01	26373
2006-04-01	25303
2006-07-01	25641
2006-10-01	27095
2007-01-01	27067
2007-04-01	28122
2007-07-01	28688
2007-10-01	28546
2008-01-01	28912
2008-04-01	30401
2008-07-01	29992
2008-10-01	29979
2009-01-01	29097
2009-04-01	31555
2009-07-01	31475
2009-10-01	31674
2010-01-01	31262
2010-04-01	31255
2010-07-01	31553
2010-10-01	31276
2011-01-01	29048
2011-04-01	32025
2011-07-01	32825
2011-10-01	32347
2012-01-01	33803
2012-04-01	34786
2012-07-01	35692
2012-10-01	39035
2013-01-01	42572
2013-04-01	45265
2013-07-01	45252
2013-10-01	47139
2014-01-01	47275
2014-04-01	48649
2014-07-01	53130
2014-10-01	54278
2015-01-01	55196
2015-04-01	56294
2015-07-01	56696
2015-10-01	56384
2016-01-01	57626
2016-04-01	58787
2016-07-01	59894
2016-10-01	61984
2017-01-01	65692
2017-04-01	66031
2017-07-01	66873
2017-10-01	68144
2018-01-01	67815