Quarter	Millions of US Dollars
1977-01-01	0
1977-04-01	0
1977-07-01	0
1977-10-01	0
1978-01-01	0
1978-04-01	0
1978-07-01	0
1978-10-01	0
1979-01-01	0
1979-04-01	0
1979-07-01	0
1979-10-01	0
1980-01-01	0
1980-04-01	0
1980-07-01	0
1980-10-01	0
1981-01-01	48
1981-04-01	42
1981-07-01	43
1981-10-01	44
1993-07-01	0
1993-10-01	0
1994-01-01	0
1994-04-01	0
1994-07-01	0
1994-10-01	0
1995-01-01	0
1995-04-01	0
1995-07-01	0
1995-10-01	0
1996-01-01	0
1996-04-01	0
1996-07-01	0
1996-10-01	0
1997-01-01	0
1997-04-01	0
1997-07-01	0
1997-10-01	0
1998-01-01	0
1998-04-01	0
1998-07-01	0
1998-10-01	0
1999-01-01	0
1999-04-01	0
1999-07-01	0
1999-10-01	0
2000-01-01	0
2000-04-01	0
2000-07-01	0
2000-10-01	0
2001-01-01	0
2001-04-01	0
2001-07-01	0
2001-10-01	0
2002-01-01	0
2002-04-01	0
2002-07-01	0
2002-10-01	0
2003-01-01	0
2003-04-01	0
2003-07-01	0
2003-10-01	0
2004-01-01	0
2004-04-01	0
2004-07-01	0
2004-10-01	0
2005-01-01	0
2005-04-01	0
2005-07-01	107
2005-10-01	655
2006-01-01	1165
2006-04-01	1397
2006-07-01	3220
2006-10-01	4527
2007-01-01	10205
2007-04-01	10390
2007-07-01	9787
2007-10-01	8898
2008-01-01	7524
2008-04-01	7020
2008-07-01	7265
2008-10-01	9089
2009-01-01	8735
2009-04-01	10897
2009-07-01	11401
2009-10-01	7957
2010-01-01	7178
2010-04-01	7867
2010-07-01	8104
2010-10-01	6517
2011-01-01	8650
2011-04-01	7155
2011-07-01	7907
2011-10-01	10291
2012-01-01	9144
2012-04-01	10574
2012-07-01	11467
2012-10-01	10024
2013-01-01	9941
2013-04-01	11289
2013-07-01	13836
2013-10-01	13353
2014-01-01	13773
2014-04-01	12481
2014-07-01	10352
2014-10-01	10462
2015-01-01	9189
2015-04-01	13573
2015-07-01	15361
2015-10-01	19389
2016-01-01	19597
2016-04-01	16554
2016-07-01	18146
2016-10-01	17596
2017-01-01	19843
2017-04-01	19734
2017-07-01	19956
2017-10-01	19015
2018-01-01	17900
2018-04-01	24721