Quarter	Millions of US Dollars
1997-10-01	1009583
1998-01-01	974775
1998-04-01	949211
1998-07-01	1010227
1998-10-01	1083331
1999-01-01	1006987
1999-04-01	969771
1999-07-01	1104466
1999-10-01	1188143
2000-01-01	1111519
2000-04-01	1093842
2000-07-01	1028617
2000-10-01	1002605
2001-01-01	928593
2001-04-01	954546
2001-07-01	961751
2001-10-01	851278
2002-01-01	806349
2002-04-01	908740
2002-07-01	869310
2002-10-01	905609
2003-01-01	874342
2003-04-01	849243
2003-07-01	876118
2003-10-01	905856
2004-01-01	915911
2004-04-01	866648
2004-07-01	841769
2004-10-01	913687
2005-01-01	846784
2005-04-01	832556
2005-07-01	802053
2005-10-01	586021
2006-01-01	534096
2006-04-01	550397
2006-07-01	544173
2006-10-01	552542
2007-01-01	544524
2007-04-01	544050
2007-07-01	589468
2007-10-01	659294
2008-01-01	716244
2008-04-01	690178
2008-07-01	689542
2008-10-01	809142
2009-01-01	719607
2009-04-01	762086
2009-07-01	789394
2009-10-01	782095
2010-01-01	725635
2010-04-01	802419
2010-07-01	840461
2010-10-01	873492
2011-01-01	820851
2011-04-01	858505
2011-07-01	891182
2011-10-01	889199
2012-01-01	806822
2012-04-01	843061
2012-07-01	855098
2012-10-01	776048
2013-01-01	676829
2013-04-01	652591
2013-07-01	653883
2013-10-01	617507
2014-01-01	601149
2014-04-01	623046
2014-07-01	573082
2014-10-01	536066
2015-01-01	514472
2015-04-01	500866
2015-07-01	502578
2015-10-01	510115
2016-01-01	534048
2016-04-01	628093
2016-07-01	633179
2016-10-01	561448
2017-01-01	565829
2017-04-01	577297
2017-07-01	552945
2017-10-01	567131
2018-01-01	576175