Quarter	Millions of US Dollars
2001-10-01	22447
2002-01-01	23398
2002-04-01	28415
2002-07-01	29155
2002-10-01	28208
2003-01-01	34512
2003-04-01	34118
2003-07-01	33805
2003-10-01	38086
2004-01-01	44267
2004-04-01	38371
2004-07-01	40230
2004-10-01	41071
2005-01-01	38836
2005-04-01	33183
2005-07-01	32854
2005-10-01	37790
2006-01-01	30525
2006-04-01	33365
2006-07-01	33816
2006-10-01	39317
2007-01-01	32043
2007-04-01	28576
2007-07-01	23171
2007-10-01	28847
2008-01-01	28053
2008-04-01	16598
2008-07-01	23439
2008-10-01	18891
2009-01-01	13034
2009-04-01	11528
2009-07-01	10079
2009-10-01	17159
2010-01-01	18841
2010-04-01	14870
2010-07-01	11492
2010-10-01	15151
2011-01-01	16987
2011-04-01	16663
2011-07-01	9991
2011-10-01	12529
2012-01-01	14580
2012-04-01	14163
2012-07-01	13320
2012-10-01	18413
2013-01-01	21177
2013-04-01	18555
2013-07-01	17015
2013-10-01	17891
2014-01-01	17273
2014-04-01	21554
2014-07-01	17757
2014-10-01	14804
2015-01-01	14937
2015-04-01	19387
2015-07-01	17748
2015-10-01	20082
2016-01-01	17080
2016-04-01	18830
2016-07-01	14352
2016-10-01	12227
2017-01-01	10705
2017-04-01	12526
2017-07-01	12649
2017-10-01	14186
2018-01-01	8396