Quarter	Millions of US Dollars
1991-07-01	31
1991-10-01	84
1992-01-01	82
1992-04-01	384
1992-07-01	1127
1992-10-01	1122
1993-01-01	1622
1993-04-01	1621
1993-07-01	1652
1993-10-01	1673
1994-01-01	1616
1994-04-01	1580
1994-07-01	1574
1994-10-01	2224
1995-01-01	3641
1995-04-01	4397
1995-07-01	5735
1995-10-01	5733
1996-01-01	8459
1996-04-01	8415
1996-07-01	9114
1996-10-01	9690
1997-01-01	12072
1997-04-01	12924
1997-07-01	13253
1997-10-01	12480
1998-01-01	13319
1998-04-01	12863
1998-07-01	13159
1998-10-01	15359
1999-01-01	14868
1999-04-01	15458
1999-07-01	19243
1999-10-01	19286
2000-01-01	19050
2000-04-01	19444
2000-07-01	18660
2000-10-01	17759
2001-01-01	16805
2001-04-01	17451
2001-07-01	18084
2001-10-01	16297
2002-01-01	14253
2002-04-01	15658
2002-07-01	14465
2002-10-01	13564
2003-01-01	12245
2003-04-01	11670
2003-07-01	14483
2003-10-01	15491
2004-01-01	15668
2004-04-01	14900
2004-07-01	14530
2004-10-01	15224
2005-01-01	14631
2005-04-01	13016
2005-07-01	12268
2005-10-01	11390
2006-01-01	10029
2006-04-01	9472
2006-07-01	9153
2006-10-01	9069
2007-01-01	8337
2007-04-01	8090
2007-07-01	8290
2007-10-01	8480
2008-01-01	8302
2008-04-01	8224
2008-07-01	8210
2008-10-01	8284
2009-01-01	7828
2009-04-01	7569
2009-07-01	6256
2009-10-01	6049
2010-01-01	6000
2010-04-01	6246
2010-07-01	6545
2010-10-01	6670
2011-01-01	6497
2011-04-01	6620
2011-07-01	6458
2011-10-01	6420
2012-01-01	6141
2012-04-01	6289
2012-07-01	6661
2012-10-01	6171
2013-01-01	5778
2013-04-01	5452
2013-07-01	4186
2013-10-01	3919
2014-01-01	3976
2014-04-01	4044
2014-07-01	3764
2014-10-01	3485
2015-01-01	3460
2015-04-01	3395
2015-07-01	3451
2015-10-01	3446
2016-01-01	3312
2016-04-01	3588
2016-07-01	3632
2016-10-01	3192
2017-01-01	3325
2017-04-01	3322
2017-07-01	3307
2017-10-01	3305
2018-01-01	2560
2018-04-01	2467