Quarter	Millions of US Dollars
1996-10-01	1000
1997-01-01	2190
1997-04-01	4947
1997-07-01	4932
1997-10-01	5417
1998-01-01	6071
1998-04-01	10884
1998-07-01	17529
1998-10-01	17426
1999-01-01	17193
1999-04-01	17089
1999-07-01	17173
1999-10-01	16799
2000-01-01	16675
2000-04-01	16395
2000-07-01	37065
2000-10-01	37201
2001-01-01	37082
2001-04-01	36602
2001-07-01	36735
2001-10-01	36331
2002-01-01	36306
2002-04-01	36356
2002-07-01	36324
2002-10-01	36399
2003-01-01	36504
2003-04-01	34960
2003-07-01	35014
2003-10-01	35250
2004-01-01	33902
2004-04-01	34160
2004-07-01	34196
2004-10-01	34397
2005-01-01	33475
2005-04-01	33408
2005-07-01	30167
2005-10-01	30148
2006-01-01	29889
2006-04-01	29427
2006-07-01	29142
2006-10-01	31690
2007-01-01	31317
2007-04-01	28931
2007-07-01	28599
2007-10-01	28641
2008-01-01	28341
2008-04-01	28338
2008-07-01	27838
2008-10-01	27808
2009-01-01	27071
2009-04-01	27135
2009-07-01	26485
2009-10-01	26467
2010-01-01	25705
2010-04-01	31110
2010-07-01	30710
2010-10-01	30688
2011-01-01	31555
2011-04-01	33383
2011-07-01	32284
2011-10-01	31740
2012-01-01	31419
2012-04-01	44045
2012-07-01	43609
2012-10-01	43665
2013-01-01	42994
2013-04-01	42855
2013-07-01	49268
2013-10-01	49265
2014-01-01	36002
2014-04-01	36093
2014-07-01	34988
2014-10-01	34172
2015-01-01	33447
2015-04-01	31560
2015-07-01	30714
2015-10-01	30516
2016-01-01	30091
2016-04-01	31863
2016-07-01	32538
2016-10-01	32090
2017-01-01	31611
2017-04-01	32589
2017-07-01	38449
2017-10-01	38461
2018-01-01	40320
2018-04-01	40272