Quarter	Millions of US Dollars
1997-10-01	932053
1998-01-01	893136
1998-04-01	872363
1998-07-01	916947
1998-10-01	960203
1999-01-01	919451
1999-04-01	900756
1999-07-01	1036705
1999-10-01	1070591
2000-01-01	1047182
2000-04-01	1016392
2000-07-01	971533
2000-10-01	924067
2001-01-01	840866
2001-04-01	843359
2001-07-01	853048
2001-10-01	767708
2002-01-01	727091
2002-04-01	808778
2002-07-01	783911
2002-10-01	807448
2003-01-01	781432
2003-04-01	756134
2003-07-01	786442
2003-10-01	810068
2004-01-01	834614
2004-04-01	785495
2004-07-01	773870
2004-10-01	834043
2005-01-01	798049
2005-04-01	776650
2005-07-01	746345
2005-10-01	517635
2006-01-01	490282
2006-04-01	506382
2006-07-01	494417
2006-10-01	496383
2007-01-01	496515
2007-04-01	473217
2007-07-01	514519
2007-10-01	569901
2008-01-01	639227
2008-04-01	592061
2008-07-01	594722
2008-10-01	698692
2009-01-01	639398
2009-04-01	673944
2009-07-01	719144
2009-10-01	704865
2010-01-01	690730
2010-04-01	753428
2010-07-01	796838
2010-10-01	814610
2011-01-01	777688
2011-04-01	793798
2011-07-01	832002
2011-10-01	811627
2012-01-01	763495
2012-04-01	772251
2012-07-01	798006
2012-10-01	710934
2013-01-01	641536
2013-04-01	611800
2013-07-01	618137
2013-10-01	574018
2014-01-01	575713
2014-04-01	587907
2014-07-01	540054
2014-10-01	495913
2015-01-01	488473
2015-04-01	467554
2015-07-01	475452
2015-10-01	476907
2016-01-01	515497
2016-04-01	598068
2016-07-01	606561
2016-10-01	528539
2017-01-01	545813
2017-04-01	547301
2017-07-01	525771
2017-10-01	529809
2018-01-01	558677