Quarter	Millions of US Dollars
1973-01-01	11
1973-04-01	12
1973-07-01	12
1973-10-01	11
1974-01-01	10
1974-04-01	10
1974-07-01	11
1974-10-01	11
1975-01-01	12
1975-04-01	12
1975-07-01	11
1975-10-01	11
1976-01-01	11
1976-04-01	11
1976-07-01	110
1976-10-01	110
1977-01-01	110
1977-04-01	141
1977-07-01	142
1977-10-01	148
1978-01-01	151
1978-04-01	152
1978-07-01	190
1978-10-01	188
1979-01-01	186
1979-04-01	187
1979-07-01	191
1979-10-01	189
1980-01-01	182
1980-04-01	142
1980-07-01	195
1980-10-01	193
1981-01-01	192
1981-04-01	190
1981-07-01	190
1981-10-01	191
1982-01-01	189
1982-04-01	188
1982-07-01	187
1982-10-01	289
1983-01-01	431
1983-04-01	581
1983-07-01	571
1983-10-01	591
1984-01-01	591
1984-04-01	591
1984-07-01	631
1984-10-01	646
1985-01-01	646
1985-04-01	646
1985-07-01	646
1985-10-01	559
1986-01-01	559
1986-04-01	612
1986-07-01	645
1986-10-01	800
1987-01-01	910
1987-04-01	1199
1987-07-01	1272
1987-10-01	1350
1988-01-01	1408
1988-04-01	1331
1988-07-01	1392
1988-10-01	1420
1989-01-01	1493
1989-04-01	1456
1989-07-01	1470
1989-10-01	1434
1990-01-01	1318
1990-04-01	1172
1990-07-01	1535
1990-10-01	1624
1991-01-01	1736
1991-04-01	1822
1991-07-01	2006
1991-10-01	2040
1992-01-01	1873
1992-04-01	1829
1992-07-01	1339
1992-10-01	978
1993-01-01	696
1993-04-01	655
1993-07-01	850
1993-10-01	1481
1994-01-01	1649
1994-04-01	1912
1994-07-01	2175
1994-10-01	2808
1995-01-01	2312
1995-04-01	2355
1995-07-01	2983
1995-10-01	3175
1996-01-01	4050
1996-04-01	4662
1996-07-01	3787
1996-10-01	4018
1997-01-01	4077
1997-04-01	4211
1997-07-01	4365
1997-10-01	4243
1998-01-01	4691
1998-04-01	5537
1998-07-01	4884
1998-10-01	3790
1999-01-01	3274
1999-04-01	3559
1999-07-01	3111
1999-10-01	3383
2000-01-01	3686
2000-04-01	4022
2000-07-01	3733
2000-10-01	3564
2001-01-01	3318
2001-04-01	2726
2001-07-01	2642
2001-10-01	2488
2002-01-01	2531
2002-04-01	2503
2002-07-01	2377
2002-10-01	2346
2003-01-01	3004
2003-04-01	3200
2003-07-01	3380
2003-10-01	3276
2004-01-01	3626
2004-04-01	3618
2004-07-01	3830
2004-10-01	4177
2005-01-01	4984
2005-04-01	4786
2005-07-01	5193
2005-10-01	5847
2006-01-01	6096
2006-04-01	5857
2006-07-01	5942
2006-10-01	5486
2007-01-01	6199
2007-04-01	7280
2007-07-01	8277
2007-10-01	8694
2008-01-01	9284
2008-04-01	9681
2008-07-01	10134
2008-10-01	9088
2009-01-01	8460
2009-04-01	10253
2009-07-01	10031
2009-10-01	9868
2010-01-01	9817
2010-04-01	9576
2010-07-01	9674
2010-10-01	9086
2011-01-01	8909
2011-04-01	10576
2011-07-01	10857
2011-10-01	11872
2012-01-01	12302
2012-04-01	12749
2012-07-01	12876
2012-10-01	13746
2013-01-01	14580
2013-04-01	13044
2013-07-01	12846
2013-10-01	12591
2014-01-01	12488
2014-04-01	11005
2014-07-01	11880
2014-10-01	11281
2015-01-01	12934
2015-04-01	13665
2015-07-01	13104
2015-10-01	12726
2016-01-01	12856
2016-04-01	12566
2016-07-01	12405
2016-10-01	12787
2017-01-01	14789
2017-04-01	14708
2017-07-01	13357
2017-10-01	14024
2018-01-01	12694
2018-04-01	13397