Year	US Dollars, Monthly Level
1988-01-01	12298410258.500800
1989-01-01	13030320750.962300
1990-01-01	15103969715.916101
1991-01-01	16617788325.316100
1992-01-01	18530632036.098600
1993-01-01	20208264998.544903
1994-01-01	23403821562.150997
1995-01-01	27931804726.583200
1996-01-01	29504974600.201797
1997-01-01	28671308979.881900
1998-01-01	26978700416.090400
1999-01-01	30636413824.591400
2000-01-01	35292687366.976400
2001-01-01	32670031429.302498
2002-01-01	32476784318.099804
2003-01-01	33662230766.996998
2004-01-01	40354947814.728195
2005-01-01	44591263750.144005
2006-01-01	47255493346.468000
2007-01-01	55968352330.605900
2008-01-01	64543898609.121400
2009-01-01	46933696340.143700
2010-01-01	58555022643.950900
2011-01-01	73035646413.921500
2012-01-01	71963871675.935000
2013-01-01	70945439257.307600
2014-01-01	71543815255.290190
2015-01-01	61287574072.243900
2016-01-01	65213486180.549690
2017-01-01	68019693850.596794