Quarter	Millions of US Dollars
1972-10-01	20
1973-01-01	20
1973-04-01	20
1973-07-01	20
1973-10-01	20
1974-01-01	20
1974-04-01	20
1974-07-01	20
1974-10-01	20
1975-01-01	55
1975-04-01	55
1975-07-01	55
1975-10-01	55
1976-01-01	55
1976-04-01	55
1976-07-01	55
1976-10-01	97
1977-01-01	139
1977-04-01	141
1977-07-01	381
1977-10-01	503
1978-01-01	667
1978-04-01	736
1978-07-01	837
1978-10-01	908
1979-01-01	935
1979-04-01	939
1979-07-01	1097
1979-10-01	1164
1980-01-01	1025
1980-04-01	1129
1980-07-01	1163
1980-10-01	1100
1981-01-01	1039
1981-04-01	931
1981-07-01	963
1981-10-01	997
1982-01-01	930
1982-04-01	909
1982-07-01	833
1982-10-01	917
1983-01-01	899
1983-04-01	870
1983-07-01	853
1983-10-01	835
1984-01-01	871
1984-04-01	818
1984-07-01	716
1984-10-01	692
1985-01-01	702
1985-04-01	706
1985-07-01	802
1985-10-01	697
1986-01-01	751
1986-04-01	666
1986-07-01	713
1986-10-01	669
1987-01-01	669
1987-04-01	659
1987-07-01	482
1987-10-01	466
1988-01-01	451
1988-04-01	414
1988-07-01	353
1988-10-01	339
1989-01-01	318
1989-04-01	297
1989-07-01	242
1989-10-01	221
1990-01-01	128
1990-04-01	112
1990-07-01	117
1990-10-01	120
1991-01-01	115
1991-04-01	116
1991-07-01	588
1991-10-01	1502
1992-01-01	1980
1992-04-01	2662
1992-07-01	2737
1992-10-01	2476
1993-01-01	2395
1993-04-01	2823
1993-07-01	3549
1993-10-01	4389
1994-01-01	4452
1994-04-01	4442
1994-07-01	4454
1994-10-01	4373
1995-01-01	4214
1995-04-01	4225
1995-07-01	4299
1995-10-01	5073
1996-01-01	5901
1996-04-01	7811
1996-07-01	8740
1996-10-01	11847
1997-01-01	11930
1997-04-01	12965
1997-07-01	14871
1997-10-01	14993
1998-01-01	15784
1998-04-01	16235
1998-07-01	15684
1998-10-01	14995
1999-01-01	13981
1999-04-01	13652
1999-07-01	13858
1999-10-01	14087
2000-01-01	14321
2000-04-01	14632
2000-07-01	14495
2000-10-01	14152
2001-01-01	14331
2001-04-01	13545
2001-07-01	13455
2001-10-01	13554
2002-01-01	13162
2002-04-01	13098
2002-07-01	12783
2002-10-01	12035
2003-01-01	12116
2003-04-01	12589
2003-07-01	13353
2003-10-01	14339
2004-01-01	14994
2004-04-01	13745
2004-07-01	12648
2004-10-01	10774
2005-01-01	10141
2005-04-01	9516
2005-07-01	9605
2005-10-01	10420
2006-01-01	11987
2006-04-01	12550
2006-07-01	13916
2006-10-01	13759
2007-01-01	14330
2007-04-01	14151
2007-07-01	13355
2007-10-01	13380
2008-01-01	12794
2008-04-01	12652
2008-07-01	11670
2008-10-01	10679
2009-01-01	10339
2009-04-01	11814
2009-07-01	13646
2009-10-01	14440
2010-01-01	16961
2010-04-01	16908
2010-07-01	18408
2010-10-01	21361
2011-01-01	20594
2011-04-01	24731
2011-07-01	26651
2011-10-01	28303
2012-01-01	31160
2012-04-01	32180
2012-07-01	34631
2012-10-01	35525
2013-01-01	35969
2013-04-01	36957
2013-07-01	35361
2013-10-01	35735
2014-01-01	35267
2014-04-01	36259
2014-07-01	37158
2014-10-01	37704
2015-01-01	36098
2015-04-01	38074
2015-07-01	37779
2015-10-01	36847
2016-01-01	37130
2016-04-01	36510
2016-07-01	35894
2016-10-01	35122
2017-01-01	34267
2017-04-01	34266
2017-07-01	34433
2017-10-01	34981
2018-01-01	36187
2018-04-01	34761