Quarter	Millions of US Dollars
1973-04-01	43
1978-04-01	25
1980-04-01	30
1982-04-01	40
1983-04-01	-25
1984-10-01	-43
1985-04-01	-30
1985-10-01	-8
1987-04-01	-32
2001-07-01	1500
2005-07-01	1250
2006-07-01	-500
2007-01-01	750
2007-07-01	1055
2008-04-01	67
2009-10-01	300
2010-04-01	1500
2011-04-01	-750
2011-07-01	-1000
2012-07-01	-989
2012-10-01	-59
2013-04-01	2700
2013-07-01	1000
2014-10-01	-3000
2015-04-01	1637
2015-07-01	-1250
2015-10-01	1044
2016-07-01	-1000
2016-10-01	4158
2017-01-01	2079
2017-04-01	1628
2017-07-01	0
2017-10-01	-1318
2018-01-01	2803
2018-04-01	4901