Quarter	Millions of US Dollars
1978-01-01	15
1981-04-01	45
1990-01-01	-15
1990-10-01	21
1991-04-01	15
1991-10-01	150
1992-01-01	145
1992-04-01	130
1992-07-01	325
1992-10-01	9
1993-01-01	74
1993-04-01	99
1993-07-01	469
1993-10-01	1655
1994-01-01	696
1994-04-01	129
1994-07-01	84
1994-10-01	731
1995-01-01	-174
1995-04-01	-47
1995-07-01	98
1995-10-01	583
1996-01-01	-28
1996-04-01	601
1996-07-01	314
1996-10-01	-168
1997-01-01	1428
1997-04-01	808
1997-07-01	1708
1997-10-01	-270
1998-01-01	724
1998-04-01	2244
1998-07-01	-43
1998-10-01	-42
1999-01-01	25
1999-04-01	747
1999-07-01	323
1999-10-01	-566
2000-01-01	117
2000-04-01	482
2000-07-01	392
2000-10-01	-1240
2001-01-01	-1
2001-04-01	-277
2001-07-01	-166
2001-10-01	-558
2002-01-01	-208
2002-04-01	-294
2002-07-01	-933
2002-10-01	-244
2003-01-01	-734
2003-04-01	-959
2003-07-01	-851
2003-10-01	100
2004-01-01	-1005
2004-04-01	-265
2004-07-01	-641
2004-10-01	-30
2005-01-01	60
2005-04-01	-512
2005-07-01	-35
2005-10-01	330
2006-01-01	67
2006-04-01	-200
2006-07-01	326
2006-10-01	220
2007-01-01	-507
2007-04-01	925
2007-07-01	-300
2007-10-01	695
2008-01-01	-309
2008-04-01	-1276
2008-07-01	-335
2009-01-01	-445
2009-04-01	-448
2009-07-01	-200
2009-10-01	-78
2010-04-01	476
2010-07-01	275
2010-10-01	413
2011-01-01	382
2011-04-01	139
2011-07-01	84
2011-10-01	-48
2012-01-01	-410
2012-04-01	13
2012-07-01	-175
2012-10-01	-12
2013-01-01	-100
2013-04-01	-7
2013-10-01	450
2014-01-01	-98
2014-04-01	1000
2014-07-01	-247
2014-10-01	-276
2015-01-01	500
2015-04-01	1500
2015-07-01	58
2015-10-01	100
2016-01-01	1360
2016-04-01	618
2016-07-01	2255
2016-10-01	161
2017-01-01	1750
2017-04-01	161
2017-07-01	800
2017-10-01	2082
2018-01-01	1233
2018-04-01	350