Year	2011 U.S. Dollars
1980-01-01	5.28
1981-01-01	5.57
1982-01-01	5.64
1983-01-01	6.33
1984-01-01	7.02
1985-01-01	7.28
1986-01-01	8.06
1987-01-01	8.35
1988-01-01	8.97
1989-01-01	9.42
1990-01-01	10.13
1991-01-01	10.86
1992-01-01	11.46
1993-01-01	11.99
1994-01-01	12.71
1995-01-01	13.44
1996-01-01	14.16
1997-01-01	14.98
1998-01-01	15.41
1999-01-01	16.67
2000-01-01	17.33
2001-01-01	17.74
2002-01-01	18.72
2003-01-01	19.54
2004-01-01	20.23
2005-01-01	21.02
2006-01-01	21.91
2007-01-01	23.14
2008-01-01	24.09
2009-01-01	24.30
2010-01-01	25.93
2011-01-01	27.14