Quarter	Millions of US Dollars
1987-01-01	72
1995-04-01	13
1996-04-01	25
1996-07-01	-27
1997-01-01	-75
1997-04-01	7
1997-07-01	7
1998-04-01	-1
1999-01-01	22
1999-04-01	-1
2000-04-01	-2
2001-01-01	-4
2001-04-01	-1
2002-01-01	-2
2002-04-01	1
2002-10-01	2
2003-04-01	-1
2003-10-01	214
2004-10-01	76
2005-04-01	-2
2006-07-01	6502
2006-10-01	-308
2008-01-01	12154
2008-04-01	806
2008-07-01	9470
2008-10-01	-693
2009-01-01	2270
2009-04-01	-6221
2009-07-01	5810
2009-10-01	-7471
2010-01-01	4140
2010-04-01	-4445
2010-07-01	3969
2010-10-01	-2793
2011-01-01	-6416
2011-04-01	-27
2011-07-01	2714
2011-10-01	6995
2012-01-01	1941
2012-04-01	-3527
2012-07-01	197
2012-10-01	7118
2013-01-01	-6072
2013-04-01	3306
2013-07-01	2705
2013-10-01	-14367
2014-01-01	734
2014-04-01	9939
2014-07-01	-1101
2014-10-01	-11201
2015-04-01	2782
2015-07-01	5883
2015-10-01	-7817
2016-01-01	-830
2016-07-01	-5698
2016-10-01	1375
2017-01-01	-1375
2017-04-01	3006
2017-07-01	-5
2017-10-01	-2915
2018-04-01	5122