Quarter	Millions of US Dollars
1997-01-01	52070
1997-04-01	57356
1997-07-01	60075
1997-10-01	60624
1998-01-01	60897
1998-04-01	60979
1998-07-01	60326
1998-10-01	60532
1999-01-01	65150
1999-04-01	63800
1999-07-01	68776
1999-10-01	69548
2000-01-01	69707
2000-04-01	67957
2000-07-01	69447
2000-10-01	70677
2001-01-01	70442
2001-04-01	74780
2001-07-01	74271
2001-10-01	72364
2002-01-01	75218
2002-04-01	79145
2002-07-01	78082
2002-10-01	79128
2003-01-01	80722
2003-04-01	81367
2003-07-01	82298
2003-10-01	82975
2004-01-01	83750
2004-04-01	85435
2004-07-01	88766
2004-10-01	90385
2005-01-01	92587
2005-04-01	93992
2005-07-01	95280
2005-10-01	95659
2006-01-01	96238
2006-04-01	97068
2006-07-01	96859
2006-10-01	98919
2007-01-01	99028
2007-04-01	103184
2007-07-01	103625
2007-10-01	104127
2008-01-01	102901
2008-04-01	103038
2008-07-01	103792
2008-10-01	103559
2009-01-01	110835
2009-04-01	120551
2009-07-01	137246
2009-10-01	153048
2010-01-01	166006
2010-04-01	172366
2010-07-01	179558
2010-10-01	186324
2011-01-01	188616
2011-04-01	204943
2011-07-01	210847
2011-10-01	216010
2012-01-01	232736
2012-04-01	239983
2012-07-01	250678
2012-10-01	256385
2013-01-01	272308
2013-04-01	293403
2013-07-01	298073
2013-10-01	309142
2014-01-01	320858
2014-04-01	333029
2014-07-01	347617
2014-10-01	350929
2015-01-01	361259
2015-04-01	363371
2015-07-01	356851
2015-10-01	380625
2016-01-01	377830
2016-04-01	387170
2016-07-01	407353
2016-10-01	413329
2017-01-01	429176
2017-04-01	444698
2017-07-01	459527
2017-10-01	482633
2018-01-01	485901