Year | Value | 2021 | 56.472 | 2020 | 56.998 | 2019 | 57.29 | 2018 | 57.35 | 2017 | 57.138 | 2016 | 57.233 | 2015 | 57.176 | 2014 | 57.075 | 2013 | 57.102 | 2012 | 57.132 | 2011 | 56.296 | 2010 | 55.831 | 2009 | 54.997 | 2008 | 54.523 | 2007 | 53.836 | 2006 | 52.82 | 2005 | 52.406 | 2004 | 51.819 | 2003 | 51.229 | 2002 | 48.791 | 2001 | 48.237 | 2000 | 47.422 | 1999 | 44.887 | 1998 | 20.276 | 1997 | 34.825 | 1996 | 33.882 | 1995 | 33.587 | 1994 | 45.825 | 1993 | 25.459 | 1992 | 25.451 | 1991 | 32.654 | 1990 | 32.376 | 1989 | 32.058 | 1988 | 12.721 | 1987 | 24.466 | 1986 | 35.579 | 1985 | 35.123 | 1984 | 34.592 | 1983 | 37.059 | 1982 | 40.051 | 1981 | 39.581 | 1980 | 39.157 | 1979 | 38.567 | 1978 | 38.313 | 1977 | 37.852 | 1976 | 37.287 | 1975 | 37.302 | 1974 | 37.055 | 1973 | 37.269 | 1972 | 34.385 | 1971 | 34.156 | 1970 | 30.269 | 1969 | 30.057 | 1968 | 30.582 | 1967 | 30.425 | 1966 | 30.192 | 1965 | 32.745 | 1964 | 35.688 | 1963 | 32.53 | 1962 | 31.656 | 1961 | 31.445 | 1960 | 31.359 |
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