Year	2011 U.S. Dollars
1970-01-01	27.41
1971-01-01	28.12
1972-01-01	28.94
1973-01-01	29.53
1974-01-01	29.59
1975-01-01	29.84
1976-01-01	31.26
1977-01-01	31.90
1978-01-01	32.08
1979-01-01	31.97
1980-01-01	32.18
1981-01-01	32.36
1982-01-01	32.84
1983-01-01	33.54
1984-01-01	34.54
1985-01-01	34.91
1986-01-01	34.75
1987-01-01	35.00
1988-01-01	35.29
1989-01-01	35.53
1990-01-01	35.70
1991-01-01	36.05
1992-01-01	36.76
1993-01-01	36.90
1994-01-01	37.55
1995-01-01	38.14
1996-01-01	38.06
1997-01-01	39.23
1998-01-01	39.95
1999-01-01	41.12
2000-01-01	42.40
2001-01-01	42.90
2002-01-01	43.61
2003-01-01	43.77
2004-01-01	43.96
2005-01-01	45.00
2006-01-01	45.54
2007-01-01	45.54
2008-01-01	45.35
2009-01-01	45.62
2010-01-01	46.20
2011-01-01	46.61