Year | Value | 2021 | 9.7382456234321 | 2020 | 9.7573660856832 | 2019 | 10.10508113622 | 2018 | 10.347956658117 | 2017 | 10.576401933865 | 2016 | 10.860321017973 | 2015 | 10.974561767359 | 2014 | 11.084686173601 | 2013 | 11.047316989448 | 2012 | 11.371341145332 | 2011 | 11.420603307903 | 2010 | 11.617708236358 | 2009 | 11.751541573508 | 2008 | 12.000263002378 | 2007 | 11.974977092504 | 2006 | 11.862011458874 | 2005 | 11.657273406269 | 2004 | 11.75307836749 | 2003 | 11.792144492207 | 2002 | 11.824070663942 | 2001 | 11.995573774348 | 2000 | 12.358315772376 | 1999 | 12.246566058928 | 1998 | 12.37275456275 | 1997 | 12.529251598372 | 1996 | 12.681706683857 | 1995 | 12.791206151403 | 1994 | 13.127059429428 | 1993 | 13.367810677279 | 1992 | 13.700377974752 | 1991 | 13.942528294626 | 1990 | 14.236335750871 | 1989 | 14.199947231966 | 1988 | 14.33133418067 | 1987 | 14.246270506741 | 1986 | 14.301903522033 | 1985 | 14.561072139943 | 1984 | 14.673904237484 | 1983 | 14.882315993998 | 1982 | 15.222159669473 | 1981 | 15.344696530133 | 1980 | 15.627360949812 | 1979 | 15.710871264912 | 1978 | 15.577534858643 | 1977 | 15.85700109092 | 1976 | 16.0332357553 | 1975 | 16.274335109994 | 1974 | 16.800324284632 | 1973 | 16.95914861816 | 1972 | 17.430707738849 | 1971 | 18.267559363189 | 1970 | 18.59131942493 | 1969 | 18.722437779709 | 1968 | 18.949535521394 | 1967 | 19.347163914265 | 1966 | 18.898124109207 | 1965 | 19.979892035556 | 1964 | 20.701913059342 | 1963 | 20.86576639945 | 1962 | 21.019852283988 | 1961 | 21.383044197236 | 1960 | 21.57023719389 |
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