Quarter	Millions of US Dollars
1981-07-01	43
1981-10-01	46
1982-01-01	40
1982-04-01	39
1982-07-01	37
1982-10-01	43
1983-01-01	42
1983-04-01	42
1983-07-01	92
1983-10-01	115
1984-01-01	117
1984-04-01	164
1984-07-01	186
1984-10-01	183
1985-01-01	183
1985-04-01	364
1985-07-01	395
1985-10-01	558
1986-01-01	587
1986-04-01	775
1986-07-01	822
1986-10-01	934
1987-01-01	975
1987-04-01	1023
1987-07-01	1230
1987-10-01	1389
1988-01-01	1374
1988-04-01	1328
1988-07-01	1371
1988-10-01	1475
1989-01-01	1438
1989-04-01	1350
1989-07-01	1330
1989-10-01	1365
1990-01-01	1570
1990-04-01	1586
1990-07-01	1704
1990-10-01	1778
1991-01-01	1840
1991-04-01	2101
1991-07-01	2326
1991-10-01	2803
1992-01-01	2986
1992-04-01	3110
1992-07-01	3825
1992-10-01	4537
1993-01-01	4806
1993-04-01	5202
1993-07-01	5590
1993-10-01	7669
1994-01-01	8284
1994-04-01	8676
1994-07-01	9145
1994-10-01	9160
1995-01-01	9535
1995-04-01	10495
1995-07-01	10451
1995-10-01	10419
1996-01-01	11146
1996-04-01	12063
1996-07-01	12823
1996-10-01	13043
1997-01-01	13183
1997-04-01	14973
1997-07-01	16415
1997-10-01	16979
1998-01-01	16917
1998-04-01	16578
1998-07-01	16311
1998-10-01	16365
1999-01-01	15949
1999-04-01	15887
1999-07-01	16403
1999-10-01	16734
2000-01-01	16637
2000-04-01	17198
2000-07-01	17697
2000-10-01	17408
2001-01-01	17015
2001-04-01	18231
2001-07-01	18333
2001-10-01	19067
2002-01-01	20173
2002-04-01	20799
2002-07-01	20961
2002-10-01	20491
2003-01-01	20345
2003-04-01	20948
2003-07-01	21324
2003-10-01	20507
2004-01-01	20767
2004-04-01	22558
2004-07-01	22392
2004-10-01	22427
2005-01-01	22190
2005-04-01	22936
2005-07-01	24134
2005-10-01	24946
2006-01-01	25211
2006-04-01	25856
2006-07-01	27328
2006-10-01	27791
2007-01-01	26749
2007-04-01	28264
2007-07-01	27601
2007-10-01	28073
2008-01-01	28127
2008-04-01	28599
2008-07-01	28167
2008-10-01	28581
2009-01-01	29115
2009-04-01	31357
2009-07-01	33525
2009-10-01	34485
2010-01-01	34138
2010-04-01	33759
2010-07-01	34330
2010-10-01	37520
2011-01-01	38461
2011-04-01	41350
2011-07-01	42050
2011-10-01	42190
2012-01-01	43530
2012-04-01	44575
2012-07-01	46919
2012-10-01	46456
2013-01-01	47428
2013-04-01	46036
2013-07-01	48399
2013-10-01	52575
2014-01-01	54088
2014-04-01	53965
2014-07-01	54361
2014-10-01	55693
2015-01-01	54882
2015-04-01	55603
2015-07-01	54499
2015-10-01	52683
2016-01-01	52655
2016-04-01	53514
2016-07-01	52958
2016-10-01	51845
2017-01-01	53156
2017-04-01	52153
2017-07-01	52874
2017-10-01	53798
2018-01-01	54352
2018-04-01	55939