Quarter	Millions of US Dollars
1991-01-01	713
1992-07-01	100
1993-07-01	202
1993-10-01	-32
1994-01-01	31
1994-04-01	352
1994-07-01	1122
1994-10-01	1918
1995-04-01	101
1995-07-01	1190
1995-10-01	995
1996-01-01	2343
1996-04-01	490
1996-07-01	1431
1996-10-01	654
1997-07-01	797
1997-10-01	3093
1998-01-01	3849
1998-04-01	-163
1998-07-01	-142
1998-10-01	483
1999-01-01	1526
1999-04-01	-273
1999-07-01	1
1999-10-01	-667
2000-01-01	2351
2000-04-01	183
2000-07-01	-144
2000-10-01	-526
2001-01-01	-302
2001-04-01	-34
2001-07-01	409
2001-10-01	830
2002-01-01	4639
2002-04-01	4
2002-07-01	-422
2002-10-01	-1167
2003-01-01	9898
2003-04-01	795
2003-07-01	-47
2003-10-01	-788
2004-01-01	-982
2004-04-01	2169
2004-07-01	-1112
2004-10-01	-2570
2005-01-01	-583
2005-04-01	2467
2005-07-01	-646
2005-10-01	0
2006-01-01	5332
2006-04-01	4538
2006-07-01	-1876
2006-10-01	-659
2007-01-01	8472
2007-04-01	8330
2007-07-01	-4007
2007-10-01	-5168
2008-01-01	-6483
2008-04-01	5669
2008-07-01	-3894
2008-10-01	941
2009-01-01	6961
2009-04-01	13177
2009-07-01	3679
2009-10-01	-11484
2010-01-01	-2330
2010-04-01	2739
2010-07-01	-516
2011-01-01	-531
2012-01-01	-19003
2012-04-01	-12039
2012-07-01	-750
2013-04-01	-8030
2013-07-01	-697
2014-04-01	7308
2014-07-01	4084
2015-07-01	-95
2016-01-01	-115
2016-04-01	-734
2016-07-01	-5974
2017-04-01	-5508
2017-07-01	-6348
2018-01-01	3700