| Year | Value | | 2021 | 10.927419638101 | | 2020 | 10.81937876441 | | 2019 | 10.842179986776 | | 2018 | 10.844498755153 | | 2017 | 10.834505967626 | | 2016 | 10.805532404678 | | 2015 | 10.76170216149 | | 2014 | 10.717767021637 | | 2013 | 10.673881569678 | | 2012 | 10.629996117719 | | 2011 | 10.691029413908 | | 2010 | 10.788003619929 | | 2009 | 10.884812199637 | | 2008 | 10.981620779345 | | 2007 | 11.069573385591 | | 2006 | 11.215445164061 | | 2005 | 11.357676078264 | | 2004 | 11.499906992467 | | 2003 | 11.640488484829 | | 2002 | 11.782741464876 | | 2001 | 11.934775130293 | | 2000 | 11.934278648803 | | 1999 | 11.93744150217 | | 1998 | 12.016670819401 | | 1997 | 12.06257527061 | | 1996 | 12.141804587841 | | 1995 | 12.300925305734 | | 1994 | 12.309306178496 | | 1993 | 12.356810664663 | | 1992 | 12.433170953694 | | 1991 | 12.524064520251 | | 1990 | 12.526800585547 | | 1989 | 12.532483468329 | | 1988 | 12.536290448056 | | 1987 | 12.539214649876 | | 1986 | 12.653755083421 | | 1985 | 12.642665185954 | | 1984 | 12.631630462106 | | 1983 | 12.620595738257 | | 1982 | 12.609561014409 | | 1981 | 12.65314817361 | | 1980 | 12.637589212984 | | 1979 | 12.622140599596 | | 1978 | 12.606691986208 | | 1977 | 12.469695889632 | | 1976 | 12.449833386705 | | 1975 | 12.443212552396 | | 1974 | 12.436481370848 | | 1973 | 12.461640541222 | | 1972 | 12.482220301199 | | 1971 | 12.508317423101 | | 1970 | 12.537504267679 | | 1969 | 12.561835833765 | | 1968 | 12.103232710629 | | 1967 | 11.740140639762 | | 1966 | 11.80359030189 | | 1965 | 11.857384580651 | | 1964 | 11.892750870584 | | 1963 | 11.963533106709 | | 1962 | 11.808826278356 | | 1961 | 11.985939113484 |
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