Quarter	Millions of US Dollars
1987-01-01	1094
1987-04-01	894
1987-07-01	1002
1987-10-01	958
1988-01-01	1227
1988-04-01	989
1988-07-01	984
1988-10-01	951
1989-01-01	869
1989-04-01	1443
1989-07-01	1618
1989-10-01	1924
1990-01-01	2479
1990-04-01	3451
1990-07-01	3318
1990-10-01	2928
1991-01-01	2413
1991-04-01	2539
1991-07-01	2262
1991-10-01	2685
1992-01-01	3777
1992-04-01	4222
1992-07-01	4234
1992-10-01	3293
1993-01-01	3570
1993-04-01	4523
1993-07-01	538
1993-10-01	636
1994-01-01	754
1994-04-01	640
1994-07-01	1059
1994-10-01	1041
1995-01-01	545
1995-04-01	527
1995-07-01	731
1995-10-01	911
1996-01-01	1257
1996-04-01	1574
1996-07-01	1860
1996-10-01	2947
1997-01-01	3801
1997-04-01	4538
1997-07-01	4783
1997-10-01	4721
1998-01-01	4998
1998-04-01	6336
1998-07-01	8195
1998-10-01	8904
1999-01-01	10400
1999-04-01	10159
1999-07-01	10810
1999-10-01	11321
2000-01-01	11844
2000-04-01	12804
2000-07-01	12584
2000-10-01	14525
2001-01-01	15987
2001-04-01	17168
2001-07-01	17896
2001-10-01	18806
2002-01-01	19192
2002-04-01	20157
2002-07-01	20090
2002-10-01	20811
2003-01-01	19314
2003-04-01	19613
2003-07-01	20081
2003-10-01	20821
2004-01-01	20741
2004-04-01	20127
2004-07-01	20954
2004-10-01	23698
2005-01-01	24855
2005-04-01	26848
2005-07-01	28911
2005-10-01	29358
2006-01-01	32166
2006-04-01	36971
2006-07-01	38938
2006-10-01	42450
2007-01-01	48193
2007-04-01	50728
2007-07-01	51354
2007-10-01	52400
2008-01-01	58393
2008-04-01	58608
2008-07-01	59846
2008-10-01	57625
2009-01-01	51266
2009-04-01	63741
2009-07-01	66380
2009-10-01	65606
2010-01-01	66703
2010-04-01	63220
2010-07-01	64976
2010-10-01	62506
2011-01-01	55975
2011-04-01	53787
2011-07-01	51577
2011-10-01	49571
2012-01-01	48976
2012-04-01	46918
2012-07-01	47231
2012-10-01	45300
2013-01-01	45431
2013-04-01	43811
2013-07-01	43228
2013-10-01	41195
2014-01-01	39460
2014-04-01	38504
2014-07-01	37560
2014-10-01	37354
2015-01-01	40420
2015-04-01	46403
2015-07-01	46679
2015-10-01	44897
2016-01-01	46662
2016-04-01	45659
2016-07-01	36755
2016-10-01	35197
2017-01-01	33970
2017-04-01	34263
2017-07-01	34343
2017-10-01	33887
2018-01-01	33095
2018-04-01	28780