Year	US Dollars, Monthly Level
1988-01-01	9371800000.000000
1989-01-01	10562200000.000000
1990-01-01	11449900000.000000
1991-01-01	11052200000.000000
1992-01-01	12253900000.000000
1993-01-01	13863000000.000000
1994-01-01	15853100000.000000
1995-01-01	17610500000.000000
1996-01-01	18763600000.000000
1997-01-01	20298500000.000000
1998-01-01	20633300000.000000
1999-01-01	22778100000.000000
2000-01-01	28340800000.000000
2001-01-01	25718200000.000000
2002-01-01	25639000000.000000
2003-01-01	27913300000.000000
2004-01-01	33812600000.000004
2005-01-01	36610800000.000000
2006-01-01	39700500000.000000
2007-01-01	45916500000.000000
2008-01-01	51320700000.000000
2009-01-01	42065400000.000000
2010-01-01	50878600000.000000
2011-01-01	58132100000.000000
2012-01-01	53972100000.000000
2013-01-01	56870900000.000000
2014-01-01	57667400000.000000
2015-01-01	53534000000.000000
2016-01-01	52188300000.000000
2017-01-01	52999900000.000000