Quarter	Millions of US Dollars
1997-01-01	350
1997-04-01	406
1997-07-01	2036
1997-10-01	2033
1998-01-01	2121
1998-04-01	2127
1998-07-01	2155
1998-10-01	2106
1999-01-01	2401
1999-04-01	2376
1999-07-01	2429
1999-10-01	2635
2000-01-01	3080
2000-04-01	3075
2000-07-01	3349
2000-10-01	3375
2001-01-01	3874
2001-04-01	3827
2001-07-01	4185
2001-10-01	4062
2002-01-01	4174
2002-04-01	4830
2002-07-01	4780
2002-10-01	5055
2003-01-01	5700
2003-04-01	6053
2003-07-01	6221
2003-10-01	6554
2004-01-01	6800
2004-04-01	7445
2004-07-01	7295
2004-10-01	7596
2005-01-01	6662
2005-04-01	6346
2005-07-01	6308
2005-10-01	6190
2006-01-01	5713
2006-04-01	5909
2006-07-01	5166
2006-10-01	5498
2007-01-01	5549
2007-04-01	5909
2007-07-01	6254
2007-10-01	6456
2008-01-01	6235
2008-04-01	5952
2008-07-01	5400
2008-10-01	5303
2009-01-01	4363
2009-04-01	5417
2009-07-01	5569
2009-10-01	7340
2010-01-01	6257
2010-04-01	5834
2010-07-01	7527
2010-10-01	7427
2011-01-01	7944
2011-04-01	8008
2011-07-01	8774
2011-10-01	8585
2012-01-01	8724
2012-04-01	10345
2012-07-01	10469
2012-10-01	11663
2013-01-01	11512
2013-04-01	13118
2013-07-01	13486
2013-10-01	15351
2014-01-01	15350
2014-04-01	15775
2014-07-01	15305
2014-10-01	15155
2015-01-01	15352
2015-04-01	15607
2015-07-01	15635
2015-10-01	16013
2016-01-01	16272
2016-04-01	16140
2016-07-01	16027
2016-10-01	15523
2017-01-01	16933
2017-04-01	15621
2017-07-01	15373
2017-10-01	16505
2018-01-01	16728
2018-04-01	17152