Quarter	Millions of US Dollars
1971-01-01	15
1972-01-01	73
1972-07-01	28
1972-10-01	29
1973-01-01	50
1973-04-01	49
1973-07-01	10
1974-01-01	15
1974-07-01	8
1974-10-01	41
1975-01-01	160
1975-04-01	202
1975-07-01	231
1975-10-01	521
1976-01-01	494
1976-04-01	268
1976-07-01	244
1976-10-01	301
1977-01-01	761
1977-04-01	857
1977-07-01	184
1977-10-01	792
1978-01-01	854
1978-04-01	768
1978-07-01	250
1978-10-01	733
1979-01-01	682
1979-04-01	410
1979-07-01	522
1979-10-01	184
1980-01-01	410
1980-04-01	60
1980-07-01	-95
1980-10-01	-212
1981-01-01	-282
1981-04-01	-145
1981-07-01	-19
1981-10-01	193
1982-01-01	-509
1982-04-01	-157
1982-07-01	198
1982-10-01	-154
1983-01-01	-197
1983-04-01	-408
1983-07-01	66
1983-10-01	-258
1984-01-01	20
1984-04-01	-108
1984-07-01	97
1984-10-01	315
1985-01-01	19
1985-04-01	111
1985-07-01	739
1985-10-01	-731
1986-01-01	367
1986-04-01	736
1986-07-01	1380
1986-10-01	922
1987-01-01	1147
1987-04-01	936
1987-07-01	-224
1987-10-01	-266
1988-01-01	1185
1988-04-01	1549
1988-07-01	608
1988-10-01	127
1989-01-01	1077
1989-04-01	1
1989-07-01	-101
1989-10-01	249
1990-01-01	-436
1990-04-01	-365
1990-07-01	-534
1990-10-01	-284
1991-01-01	-638
1991-04-01	-386
1991-07-01	640
1991-10-01	-27
1992-01-01	704
1992-04-01	1181
1992-07-01	-428
1992-10-01	-584
1993-01-01	-255
1993-04-01	708
1993-07-01	-357
1993-10-01	-680
1994-01-01	-488
1994-04-01	-155
1994-07-01	121
1994-10-01	-772
1995-01-01	-253
1995-04-01	-939
1995-07-01	278
1995-10-01	-202
1996-01-01	997
1996-04-01	598
1996-07-01	-776
1996-10-01	294
1997-01-01	614
1997-04-01	-197
1997-07-01	3461
1997-10-01	-15
1998-01-01	1759
1998-04-01	3091
1998-07-01	858
1998-10-01	18
1999-01-01	1706
1999-04-01	1759
1999-07-01	355
1999-10-01	-621
2000-01-01	3251
2000-04-01	3058
2000-07-01	2042
2000-10-01	-231
2001-01-01	1396
2001-04-01	1199
2001-07-01	-752
2001-10-01	533
2002-01-01	1958
2002-04-01	1928
2002-07-01	-946
2002-10-01	1793
2003-01-01	2339
2003-04-01	2517
2003-07-01	1985
2003-10-01	2840
2004-01-01	1294
2004-04-01	2589
2004-07-01	803
2004-10-01	5677
2005-01-01	1974
2005-04-01	2351
2005-07-01	371
2005-10-01	4074
2006-01-01	3821
2006-04-01	9051
2006-07-01	6898
2006-10-01	7363
2007-01-01	7683
2007-04-01	1123
2007-07-01	6711
2007-10-01	9949
2008-01-01	13922
2008-04-01	13004
2008-07-01	1705
2008-10-01	1202
2009-01-01	4351
2009-04-01	2322
2009-07-01	1855
2009-10-01	187
2010-01-01	11919
2010-04-01	3076
2010-07-01	6026
2010-10-01	-2594
2011-01-01	19448
2011-04-01	1980
2011-07-01	1853
2011-10-01	13674
2012-01-01	18217
2012-04-01	10709
2012-07-01	4194
2012-10-01	-1168
2013-01-01	-235
2013-04-01	8359
2013-07-01	2935
2013-10-01	10176
2014-01-01	895
2014-04-01	-6283
2014-07-01	-2009
2014-10-01	2364
2015-01-01	4664
2015-04-01	-8325
2015-07-01	840
2015-10-01	-6345
2016-01-01	-2872
2016-04-01	900
2016-07-01	3519
2016-10-01	-9926
2017-01-01	9133
2017-04-01	-8700
2017-07-01	-2872
2017-10-01	949
2018-01-01	354
2018-04-01	-915