Year	2011 U.S. Dollars
1970-01-01	29.63
1971-01-01	31.40
1972-01-01	33.28
1973-01-01	34.81
1974-01-01	36.10
1975-01-01	37.66
1976-01-01	39.78
1977-01-01	41.20
1978-01-01	43.01
1979-01-01	44.88
1980-01-01	45.80
1981-01-01	46.20
1982-01-01	46.58
1983-01-01	48.66
1984-01-01	51.31
1985-01-01	52.80
1986-01-01	53.33
1987-01-01	54.17
1988-01-01	54.28
1989-01-01	56.53
1990-01-01	58.44
1991-01-01	60.95
1992-01-01	62.82
1993-01-01	64.26
1994-01-01	66.68
1995-01-01	68.84
1996-01-01	71.17
1997-01-01	73.12
1998-01-01	73.22
1999-01-01	74.12
2000-01-01	77.06
2001-01-01	79.75
2002-01-01	81.50
2003-01-01	84.06
2004-01-01	85.78
2005-01-01	86.74
2006-01-01	86.06
2007-01-01	84.50
2008-01-01	81.68
2009-01-01	81.70
2010-01-01	81.61
2011-01-01	81.47