Year	US Dollars, Monthly Level
1988-01-01	12287200000.000000
1989-01-01	13030100000.000000
1990-01-01	15107300000.000000
1991-01-01	16674299999.999998
1992-01-01	18537600000.000000
1993-01-01	20208900000.000000
1994-01-01	23369300000.000000
1995-01-01	27981900000.000000
1996-01-01	29583700000.000000
1997-01-01	28683500000.000000
1998-01-01	27010700000.000000
1999-01-01	30629700000.000000
2000-01-01	35221000000.000000
2001-01-01	32696199999.999996
2002-01-01	32556600000.000004
2003-01-01	33707400000.000000
2004-01-01	40356700000.000000
2005-01-01	44456700000.000000
2006-01-01	47317900000.000000
2007-01-01	56105700000.000000
2008-01-01	64531400000.000010
2009-01-01	46927300000.000000
2010-01-01	58704500000.000000
2011-01-01	72747100000.000000
2012-01-01	72270400000.000000
2013-01-01	71102000000.000000
2014-01-01	71479600000.000000
2015-01-01	61337300000.000000
2016-01-01	65064700000.000000
2017-01-01	68006299999.999990