Quarter	Millions of US Dollars
1968-07-01	0
1968-10-01	0
1969-01-01	0
1969-04-01	0
1969-07-01	0
1969-10-01	0
1970-01-01	0
1970-04-01	0
1970-07-01	0
1970-10-01	0
1971-01-01	0
1971-04-01	0
1971-07-01	0
1971-10-01	0
1972-01-01	0
1972-04-01	0
1972-07-01	0
1972-10-01	0
1973-01-01	0
1973-04-01	0
1973-07-01	0
1973-10-01	0
1974-01-01	0
1974-04-01	0
1974-07-01	0
1974-10-01	0
1975-01-01	0
1975-04-01	0
1975-07-01	0
1975-10-01	0
1976-01-01	0
1976-04-01	0
1976-07-01	0
1976-10-01	0
1977-01-01	0
1977-04-01	0
1977-07-01	0
1977-10-01	0
1978-01-01	0
1978-04-01	18
1978-07-01	44
1978-10-01	44
1979-01-01	44
1979-04-01	50
1979-07-01	26
1979-10-01	26
1980-01-01	24
1980-04-01	4
1980-07-01	4
1980-10-01	57
1981-01-01	82
1981-04-01	79
1981-07-01	79
1981-10-01	25
1982-01-01	63
1982-04-01	97
1982-07-01	97
1982-10-01	98
1983-01-01	141
1983-04-01	238
1983-07-01	333
1983-10-01	366
1984-01-01	305
1984-04-01	164
1984-07-01	154
1984-10-01	402
1985-01-01	411
1985-04-01	482
1985-07-01	564
1985-10-01	334
1986-01-01	311
1986-04-01	331
1986-07-01	222
1986-10-01	190
1987-01-01	758
1987-04-01	1158
1987-07-01	1241
1987-10-01	1478
1988-01-01	1194
1988-04-01	1022
1988-07-01	1249
1988-10-01	1325
1989-01-01	1144
1989-04-01	1352
1989-07-01	1516
1989-10-01	2076
1990-01-01	2027
1990-04-01	1610
1990-07-01	1517
1990-10-01	1054
1991-01-01	1708
1991-04-01	1915
1991-07-01	1823
1991-10-01	3408
1992-01-01	3114
1992-04-01	3522
1992-07-01	5470
1992-10-01	5199
1993-01-01	5026
1993-04-01	5192
1993-07-01	4538
1993-10-01	4061
1994-01-01	4481
1994-04-01	5158
1994-07-01	5204
1994-10-01	5693
1995-01-01	6664
1995-04-01	7923
1995-07-01	8537
1995-10-01	8513
1996-01-01	7788
1996-04-01	7898
1996-07-01	8393
1996-10-01	11911
1997-01-01	12528
1997-04-01	13854
1997-07-01	14410
1997-10-01	13429
1998-01-01	14094
1998-04-01	16557
1998-07-01	17634
1998-10-01	22191
1999-01-01	22050
1999-04-01	22346
1999-07-01	21932
1999-10-01	18798
2000-01-01	20126
2000-04-01	19820
2000-07-01	21704
2000-10-01	23165
2001-01-01	22943
2001-04-01	24969
2001-07-01	23614
2001-10-01	25434
2002-01-01	22955
2002-04-01	23274
2002-07-01	21783
2002-10-01	21482
2003-01-01	22589
2003-04-01	23798
2003-07-01	26614
2003-10-01	27201
2004-01-01	24897
2004-04-01	21495
2004-07-01	22701
2004-10-01	25965
2005-01-01	27432
2005-04-01	30737
2005-07-01	27012
2005-10-01	27708
2006-01-01	31366
2006-04-01	35979
2006-07-01	41899
2006-10-01	41941
2007-01-01	42273
2007-04-01	42555
2007-07-01	41706
2007-10-01	44358
2008-01-01	49574
2008-04-01	51621
2008-07-01	51407
2008-10-01	48561
2009-01-01	48225
2009-04-01	50353
2009-07-01	53564
2009-10-01	51502
2010-01-01	48284
2010-04-01	52496
2010-07-01	55047
2010-10-01	57807
2011-01-01	67367
2011-04-01	74039
2011-07-01	73968
2011-10-01	86262
2012-01-01	91439
2012-04-01	91160
2012-07-01	96387
2012-10-01	90026
2013-01-01	102260
2013-04-01	123388
2013-07-01	145040
2013-10-01	158216
2014-01-01	180458
2014-04-01	180196
2014-07-01	184414
2014-10-01	196091
2015-01-01	197594
2015-04-01	205785
2015-07-01	195116
2015-10-01	210840
2016-01-01	205689
2016-04-01	230332
2016-07-01	239303
2016-10-01	242944
2017-01-01	254102
2017-04-01	262301
2017-07-01	268990
2017-10-01	289673
2018-01-01	297710
2018-04-01	317067