Year | Value | 2021 | 53.429 | 2020 | 53.906 | 2019 | 54.471 | 2018 | 54.487 | 2017 | 53.455 | 2016 | 53.829 | 2015 | 53.927 | 2014 | 52.889 | 2013 | 54.366 | 2012 | 54.556 | 2011 | 53.54 | 2010 | 53.733 | 2009 | 52.724 | 2008 | 52.483 | 2007 | 51.802 | 2006 | 51.135 | 2005 | 50.602 | 2004 | 49.925 | 2003 | 49.181 | 2002 | 46.111 | 2001 | 45.434 | 2000 | 44.538 | 1999 | 41.481 | 1998 | 16.723 | 1997 | 29.803 | 1996 | 28.872 | 1995 | 28.488 | 1994 | 42.84 | 1993 | 20.353 | 1992 | 20.403 | 1991 | 27.826 | 1990 | 27.671 | 1989 | 27.473 | 1988 | 12.037 | 1987 | 19.747 | 1986 | 31.747 | 1985 | 31.253 | 1984 | 30.82 | 1983 | 33.925 | 1982 | 38.123 | 1981 | 37.931 | 1980 | 37.625 | 1979 | 37.221 | 1978 | 36.935 | 1977 | 36.754 | 1976 | 36.35 | 1975 | 36.139 | 1974 | 35.922 | 1973 | 35.627 | 1972 | 29.491 | 1971 | 29.098 | 1970 | 23.156 | 1969 | 22.83 | 1968 | 23.514 | 1967 | 23.172 | 1966 | 22.851 | 1965 | 26.366 | 1964 | 30.838 | 1963 | 25.788 | 1962 | 26.868 | 1961 | 26.552 | 1960 | 26.319 |
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