Quarter	Millions of US Dollars
1997-07-01	150
1998-01-01	150
1998-04-01	169
1999-04-01	-100
2000-07-01	-150
2001-01-01	-150
2001-04-01	-56
2001-10-01	150
2002-01-01	525
2002-04-01	600
2002-10-01	1630
2003-01-01	2050
2003-04-01	150
2003-10-01	25
2004-01-01	455
2004-04-01	775
2004-07-01	200
2004-10-01	270
2005-01-01	300
2005-04-01	-250
2005-07-01	-30
2005-10-01	-40
2006-01-01	-148
2006-04-01	417
2006-07-01	275
2006-10-01	582
2007-01-01	1375
2007-04-01	1903
2007-07-01	183
2007-10-01	-526
2008-04-01	1650
2008-07-01	3500
2009-01-01	-826
2009-04-01	2313
2009-07-01	-300
2009-10-01	-527
2010-01-01	50
2010-04-01	2250
2010-07-01	-200
2010-10-01	1058
2011-01-01	3540
2011-04-01	263
2011-07-01	-100
2011-10-01	100
2012-01-01	-300
2012-04-01	150
2012-07-01	2684
2012-10-01	3343
2013-01-01	2443
2013-04-01	4959
2013-07-01	-1850
2013-10-01	1848
2014-01-01	-614
2014-04-01	-333
2014-10-01	675
2015-01-01	-350
2015-10-01	-2
2016-01-01	-593
2016-04-01	-250
2016-07-01	-394
2016-10-01	1733
2017-01-01	-973
2017-04-01	-235
2017-07-01	388
2017-10-01	-491
2018-01-01	-1454
2018-04-01	-2486