Quarter	Millions of US Dollars
1972-01-01	42
1972-04-01	42
1972-07-01	62
1972-10-01	96
1973-01-01	96
1973-04-01	96
1973-07-01	134
1973-10-01	178
1974-01-01	178
1974-04-01	177
1974-07-01	177
1974-10-01	227
1975-01-01	320
1975-04-01	345
1975-07-01	368
1975-10-01	394
1976-01-01	395
1976-04-01	396
1976-07-01	398
1976-10-01	497
1977-01-01	538
1977-04-01	661
1977-07-01	1188
1977-10-01	1606
1978-01-01	1962
1978-04-01	2123
1978-07-01	2379
1978-10-01	2603
1979-01-01	2668
1979-04-01	2679
1979-07-01	2954
1979-10-01	3022
1980-01-01	2847
1980-04-01	3211
1980-07-01	3230
1980-10-01	3204
1981-01-01	3091
1981-04-01	3305
1981-07-01	3741
1981-10-01	4267
1982-01-01	4303
1982-04-01	4350
1982-07-01	4201
1982-10-01	4302
1983-01-01	4217
1983-04-01	4144
1983-07-01	4065
1983-10-01	3888
1984-01-01	3946
1984-04-01	3804
1984-07-01	3554
1984-10-01	3504
1985-01-01	3526
1985-04-01	3516
1985-07-01	3659
1985-10-01	3452
1986-01-01	3550
1986-04-01	3514
1986-07-01	3573
1986-10-01	3295
1987-01-01	3227
1987-04-01	3103
1987-07-01	2924
1987-10-01	2837
1988-01-01	2772
1988-04-01	2367
1988-07-01	1850
1988-10-01	1578
1989-01-01	1524
1989-04-01	1358
1989-07-01	1234
1989-10-01	1264
1990-01-01	2190
1990-04-01	2778
1990-07-01	3113
1990-10-01	3506
1991-01-01	3690
1991-04-01	4578
1991-07-01	5226
1991-10-01	6664
1992-01-01	7538
1992-04-01	8564
1992-07-01	9513
1992-10-01	10663
1993-01-01	11182
1993-04-01	13773
1993-07-01	18219
1993-10-01	21739
1994-01-01	25307
1994-04-01	25478
1994-07-01	25823
1994-10-01	26048
1995-01-01	24050
1995-04-01	24040
1995-07-01	24413
1995-10-01	25763
1996-01-01	26977
1996-04-01	30091
1996-07-01	31352
1996-10-01	35155
1997-01-01	36757
1997-04-01	41030
1997-07-01	46897
1997-10-01	46819
1998-01-01	49335
1998-04-01	52420
1998-07-01	52705
1998-10-01	52237
1999-01-01	50802
1999-04-01	53669
1999-07-01	54687
1999-10-01	54153
2000-01-01	55577
2000-04-01	56465
2000-07-01	56831
2000-10-01	54378
2001-01-01	55268
2001-04-01	54653
2001-07-01	55387
2001-10-01	55322
2002-01-01	52830
2002-04-01	51693
2002-07-01	49590
2002-10-01	49680
2003-01-01	48109
2003-04-01	47094
2003-07-01	47259
2003-10-01	49815
2004-01-01	49745
2004-04-01	46210
2004-07-01	44155
2004-10-01	43110
2005-01-01	44241
2005-04-01	43858
2005-07-01	44857
2005-10-01	46959
2006-01-01	48942
2006-04-01	49256
2006-07-01	50764
2006-10-01	52959
2007-01-01	53580
2007-04-01	62519
2007-07-01	60835
2007-10-01	63548
2008-01-01	62376
2008-04-01	60764
2008-07-01	59266
2008-10-01	55523
2009-01-01	56003
2009-04-01	57092
2009-07-01	66048
2009-10-01	76298
2010-01-01	86079
2010-04-01	92004
2010-07-01	98154
2010-10-01	103254
2011-01-01	112771
2011-04-01	122247
2011-07-01	124756
2011-10-01	135847
2012-01-01	144899
2012-04-01	149430
2012-07-01	162415
2012-10-01	168982
2013-01-01	177224
2013-04-01	186457
2013-07-01	198516
2013-10-01	214138
2014-01-01	217865
2014-04-01	229448
2014-07-01	238896
2014-10-01	243478
2015-01-01	244915
2015-04-01	260267
2015-07-01	261080
2015-10-01	258442
2016-01-01	277827
2016-04-01	277910
2016-07-01	281706
2016-10-01	288732
2017-01-01	294233
2017-04-01	298097
2017-07-01	315027
2017-10-01	315878
2018-01-01	323686
2018-04-01	324290