Quarter	Millions of US Dollars
2007-07-01	275
2007-10-01	1
2008-01-01	1
2008-04-01	1
2008-07-01	1
2008-10-01	1
2009-01-01	1
2009-04-01	1
2009-07-01	1
2009-10-01	1
2010-01-01	1
2010-04-01	1
2010-07-01	-283
2011-01-01	0
2011-04-01	400
2012-07-01	845
2013-01-01	300
2013-07-01	335
2014-01-01	225
2014-04-01	180
2014-07-01	422
2014-10-01	98
2015-01-01	1280
2016-04-01	280
2017-01-01	106
2017-04-01	967
2017-07-01	-225
2017-10-01	610
2018-01-01	213
2018-04-01	450