Quarter	Millions of US Dollars
1972-10-01	10
1973-01-01	14
1979-10-01	-10
1988-01-01	-14
1996-10-01	75
1997-07-01	200
1997-10-01	-5
1998-04-01	250
1999-10-01	-70
2000-01-01	196
2000-07-01	225
2001-01-01	166
2001-04-01	400
2001-10-01	250
2002-04-01	300
2002-07-01	-200
2003-01-01	-215
2004-01-01	248
2004-04-01	125
2004-07-01	34
2004-10-01	186
2005-04-01	50
2005-07-01	500
2005-10-01	250
2006-01-01	350
2006-07-01	330
2006-10-01	200
2007-01-01	1750
2007-04-01	125
2007-07-01	-225
2007-10-01	150
2008-04-01	350
2009-01-01	60
2009-07-01	146
2009-10-01	500
2010-01-01	761
2010-07-01	-14
2010-10-01	300
2011-01-01	386
2011-04-01	-400
2011-07-01	-14
2011-10-01	574
2012-01-01	250
2012-07-01	786
2012-10-01	-1400
2013-01-01	1200
2013-07-01	-29
2013-10-01	500
2014-01-01	-14
2014-04-01	-270
2014-07-01	786
2014-10-01	-187
2015-01-01	925
2015-04-01	-1100
2015-07-01	1971
2016-07-01	563
2017-04-01	-675
2017-07-01	869