Quarter	Millions of US Dollars
1999-04-01	15579
1999-07-01	12360
1999-10-01	36350
2000-01-01	33879
2000-04-01	40301
2000-07-01	43250
2000-10-01	40891
2001-01-01	38486
2001-04-01	35354
2001-07-01	41708
2001-10-01	37721
2002-01-01	40479
2002-04-01	45834
2002-07-01	44250
2002-10-01	44023
2003-01-01	43628
2003-04-01	46550
2003-07-01	45583
2003-10-01	46338
2004-01-01	45339
2004-04-01	41010
2004-07-01	43121
2004-10-01	42982
2005-01-01	43115
2005-04-01	41484
2005-07-01	39494
2005-10-01	40675
2006-01-01	44084
2006-04-01	43970
2006-07-01	46041
2006-10-01	46562
2007-01-01	48090
2007-04-01	50340
2007-07-01	51658
2007-10-01	50865
2008-01-01	54416
2008-04-01	56365
2008-07-01	56946
2008-10-01	48982
2009-01-01	46826
2009-04-01	54258
2009-07-01	59139
2009-10-01	61504
2010-01-01	65389
2010-04-01	68541
2010-07-01	72321
2010-10-01	71387
2011-01-01	77534
2011-04-01	80561
2011-07-01	76756
2011-10-01	79663
2012-01-01	82957
2012-04-01	83857
2012-07-01	78501
2012-10-01	85124
2013-01-01	88623
2013-04-01	89533
2013-07-01	82548
2013-10-01	82062
2014-01-01	94973
2014-04-01	96796
2014-07-01	99404
2014-10-01	99119
2015-01-01	101259
2015-04-01	102868
2015-07-01	96839
2015-10-01	107186
2016-01-01	120744
2016-04-01	126917
2016-07-01	135940
2016-10-01	133764
2017-01-01	143885
2017-04-01	147731
2017-07-01	152929
2017-10-01	155740
2018-01-01	159609