Year | Value | 2021 | 32.957395546878 | 2020 | 32.96386390775 | 2019 | 32.823563424755 | 2018 | 32.80324967218 | 2017 | 32.852470173255 | 2016 | 33.031310625396 | 2015 | 33.162125122737 | 2014 | 33.141197693733 | 2013 | 33.341665156281 | 2012 | 33.344680310482 | 2011 | 33.336129639863 | 2010 | 33.411869278426 | 2009 | 33.340110637799 | 2008 | 33.474857459005 | 2007 | 33.740544752394 | 2006 | 33.683561188473 | 2005 | 33.697507520987 | 2004 | 33.637005932073 | 2003 | 33.565011272771 | 2002 | 33.558891327975 | 2001 | 33.523042431644 | 2000 | 33.648812152072 | 1999 | 33.675448099242 | 1998 | 33.646173052156 | 1997 | 33.531997636155 | 1996 | 33.487802014998 | 1995 | 33.453901504741 | 1994 | 33.503271670952 | 1993 | 33.565026920846 | 1992 | 33.60055985115 | 1991 | 33.667074184587 | 1990 | 33.666360835989 | 1989 | 33.553664203506 | 1988 | 33.560697872301 | 1987 | 33.572116043632 | 1986 | 33.566752531502 | 1985 | 33.564441584774 | 1984 | 33.431999888195 | 1983 | 33.251184528167 | 1982 | 32.998858185856 | 1981 | 32.870244558583 | 1980 | 32.719315213447 | 1979 | 32.422624380056 | 1978 | 32.135915850215 | 1977 | 31.842037689413 | 1976 | 31.50904795837 | 1975 | 31.182831562412 | 1974 | 30.923655826492 | 1973 | 30.679120000965 | 1972 | 30.437269677519 | 1971 | 30.148501512548 | 1970 | 29.853898993023 | 1969 | 29.632736598273 | 1968 | 29.506239221889 | 1967 | 29.317661522935 | 1966 | 29.173227616755 | 1965 | 29.013602466313 | 1964 | 28.842861649766 | 1963 | 28.643522032934 | 1962 | 28.475421872163 | 1961 | 28.288184430574 |
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