Quarter	Millions of US Dollars
1978-01-01	20
1980-04-01	50
1980-07-01	12
1980-10-01	46
1985-01-01	-20
1985-04-01	-50
1985-10-01	-40
1990-04-01	565
1990-10-01	-15
1994-01-01	50
1996-10-01	-67
1997-01-01	-50
1997-07-01	12
1997-10-01	8
1998-01-01	-12
1998-04-01	192
1998-10-01	-67
1999-04-01	300
2000-04-01	-2
2000-07-01	250
2000-10-01	-10
2001-01-01	250
2001-04-01	-17
2001-10-01	-10
2002-01-01	250
2002-04-01	-10
2002-10-01	-10
2003-01-01	450
2003-04-01	-356
2003-10-01	40
2004-01-01	96
2008-01-01	-200
2009-04-01	-300
2011-01-01	-250
2011-10-01	250
2012-01-01	-250
2012-04-01	250
2012-10-01	1000
2013-01-01	-250
2013-04-01	1500
2013-07-01	500
2013-10-01	960
2014-01-01	-310
2014-04-01	1000
2015-01-01	1000
2016-04-01	500
2017-07-01	400