Year	2011 U.S. Dollars
1970-01-01	20.21
1971-01-01	21.09
1972-01-01	22.14
1973-01-01	23.27
1974-01-01	24.21
1975-01-01	25.12
1976-01-01	26.29
1977-01-01	27.38
1978-01-01	28.22
1979-01-01	29.03
1980-01-01	29.27
1981-01-01	29.76
1982-01-01	30.07
1983-01-01	31.06
1984-01-01	31.88
1985-01-01	32.61
1986-01-01	33.11
1987-01-01	33.56
1988-01-01	34.42
1989-01-01	35.62
1990-01-01	36.88
1991-01-01	40.95
1992-01-01	41.98
1993-01-01	42.57
1994-01-01	43.72
1995-01-01	44.76
1996-01-01	45.67
1997-01-01	46.72
1998-01-01	47.24
1999-01-01	47.66
2000-01-01	48.97
2001-01-01	50.18
2002-01-01	50.89
2003-01-01	51.33
2004-01-01	51.76
2005-01-01	52.38
2006-01-01	54.29
2007-01-01	55.20
2008-01-01	55.13
2009-01-01	53.76
2010-01-01	54.50
2011-01-01	55.26