Year US Dollars 1960 4.9245 1961 4.44334 1962 3.82805 1963 4.01611 1964 2.10401 1965 1.5768 1966 1.85419 1967 2.16916 1968 1.56109 1969 1.90128 1970 2.80688 1971 6.00927 1972 9.9242 1973 21.25983 1974 44.50193 1975 12.07505 1976 0.11416 1977 0.04967 1978 0.04529 1979 17.84425 1980 43.34115 1981 17.66839 1982 5.4217 1983 5.67135 1984 3.05723 1985 1.87633 1986 1.99835 1987 2.08386 1988 2.45109 1989 2.88417 1990 4.63594 1991 9.68857 1992 20.01602 1993 28.75273 1994 27.92216 1995 46.30053 1996 34.38106 1997 28.4038 1998 26.42368 1999 21.11857 2000 28.51428 2001 29.74504 2002 32.42296 2003 34.65515 2004 31.26985 2005 34.18995 2006 35.34336 2007 46.38569 2008 43.93036 2009 45.06511 2010 47.41452 2011 47.47876 2012 54.62296 2013 53.88181 2014 52.77034 2015 44.04339 2016 46.62204 2017 54.08861 2018 48.88539 2019 59.62828 2020 83.75018 2021 81.91079