Year | Value | 2021 | 8.449007719347 | 2020 | 8.473932430616 | 2019 | 8.5473112567145 | 2018 | 8.7170197119438 | 2017 | 8.8127591320401 | 2016 | 8.6122122391141 | 2015 | 8.4777113262223 | 2014 | 8.0665208312618 | 2013 | 8.2606355682942 | 2012 | 8.3091141778201 | 2011 | 7.9204658501194 | 2010 | 8.2391848750741 | 2009 | 8.2198290532427 | 2008 | 7.8782974591358 | 2007 | 7.8903573176701 | 2006 | 8.1192222916735 | 2005 | 8.3044248257198 | 2004 | 8.3925156147601 | 2003 | 8.7298858710673 | 2002 | 9.2004321621016 | 2001 | 8.8808852126756 | 2000 | 8.932872696241 | 1999 | 9.0255574507461 | 1998 | 9.014568930248 | 1997 | 9.5019819016503 | 1996 | 9.650240031351 | 1995 | 9.7784075365287 | 1994 | 9.5531565426137 | 1993 | 10.548804913874 | 1992 | 9.2598460682623 | 1991 | 10.448088049337 | 1990 | 9.9074686524278 | 1989 | 9.8471571810268 | 1988 | 9.8501070663812 | 1987 | 10.068690189632 | 1986 | 10.770874132099 | 1985 | 10.940427126265 | 1984 | 10.238055601798 | 1983 | 11.636524782054 | 1982 | 11.032758806919 | 1981 | 11.648898918372 | 1980 | 11.821790223778 | 1979 | 12.264372311302 | 1978 | 11.670987804209 | 1977 | 11.81871689229 | 1976 | 11.900639108397 | 1975 | 12.413662149011 | 1974 | 12.017276827694 | 1973 | 12.059615152854 | 1972 | 12.241787463112 | 1971 | 12.417936837969 | 1970 | 12.693900151236 | 1969 | 12.470388041774 | 1968 | 12.602458153268 | 1967 | 11.198160606319 | 1966 | 11.738261738262 | 1965 | 11.886930472342 | 1964 | 11.602521215536 | 1963 | 12.961480295347 | 1962 | 11.897808251184 | 1961 | 13.336357450669 | 1960 | 12.355063836023 |
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