Quarter	Millions of US Dollars
1981-10-01	107
1982-01-01	105
1982-04-01	104
1982-07-01	103
1982-10-01	104
1983-01-01	103
1983-04-01	102
1983-07-01	103
1983-10-01	103
1984-01-01	103
1984-04-01	102
1984-07-01	100
1984-10-01	99
1985-01-01	249
1985-04-01	249
1985-07-01	251
1985-10-01	304
1986-01-01	490
1986-04-01	500
1986-07-01	507
1986-10-01	503
1987-01-01	605
1987-04-01	599
1987-07-01	600
1987-10-01	646
1988-01-01	637
1988-04-01	713
1988-07-01	850
1988-10-01	905
1989-01-01	872
1989-04-01	984
1989-07-01	1004
1989-10-01	1204
1990-01-01	1295
1990-04-01	1315
1990-07-01	1530
1990-10-01	1773
1991-01-01	1702
1991-04-01	1694
1991-07-01	1747
1991-10-01	1819
1992-01-01	1595
1992-04-01	1661
1992-07-01	1733
1992-10-01	1567
1993-01-01	1407
1993-04-01	1450
1993-07-01	1532
1993-10-01	1638
1994-01-01	1731
1994-04-01	1905
1994-07-01	2182
1994-10-01	1969
1995-01-01	2118
1995-04-01	2138
1995-07-01	2167
1995-10-01	2135
1996-01-01	2222
1996-04-01	2386
1996-07-01	2674
1996-10-01	2847
1997-01-01	3143
1997-04-01	3468
1997-07-01	4033
1997-10-01	4040
1998-01-01	4021
1998-04-01	3884
1998-07-01	3704
1998-10-01	3768
1999-01-01	3680
1999-04-01	3261
1999-07-01	2988
1999-10-01	2773
2000-01-01	2444
2000-04-01	2399
2000-07-01	2386
2000-10-01	2395
2001-01-01	2360
2001-04-01	2244
2001-07-01	2263
2001-10-01	2256
2002-01-01	2102
2002-04-01	2132
2002-07-01	2093
2002-10-01	2182
2003-01-01	2182
2003-04-01	2187
2003-07-01	2291
2003-10-01	2099
2004-01-01	2600
2004-04-01	3449
2004-07-01	3661
2004-10-01	4273
2005-01-01	4894
2005-04-01	5384
2005-07-01	5957
2005-10-01	6622
2006-01-01	9169
2006-04-01	11442
2006-07-01	11975
2006-10-01	12734
2007-01-01	14800
2007-04-01	16418
2007-07-01	18251
2007-10-01	19320
2008-01-01	19629
2008-04-01	19748
2008-07-01	19567
2008-10-01	19571
2009-01-01	19084
2009-04-01	18366
2009-07-01	19214
2009-10-01	20884
2010-01-01	20919
2010-04-01	20537
2010-07-01	20042
2010-10-01	19470
2011-01-01	17252
2011-04-01	15382
2011-07-01	16651
2011-10-01	16060
2012-01-01	14251
2012-04-01	12329
2012-07-01	10393
2012-10-01	11614
2013-01-01	12169
2013-04-01	12788
2013-07-01	13790
2013-10-01	13775
2014-01-01	13909
2014-04-01	14450
2014-07-01	17459
2014-10-01	16884
2015-01-01	18122
2015-04-01	19939
2015-07-01	20684
2015-10-01	20465
2016-01-01	20787
2016-04-01	20769
2016-07-01	21658
2016-10-01	22595
2017-01-01	24133
2017-04-01	25788
2017-07-01	26044
2017-10-01	27577
2018-01-01	27193
2018-04-01	26451