Year | Value | 2021 | 9.5774990122853 | 2020 | 9.2699174819523 | 2019 | 9.0469540376853 | 2018 | 9.1987890237681 | 2017 | 9.3558854236282 | 2016 | 9.551807382785 | 2015 | 9.7121309195792 | 2014 | 9.8755649614607 | 2013 | 10.019251139997 | 2012 | 10.197946418488 | 2011 | 10.353641003393 | 2010 | 10.769299408855 | 2009 | 10.890535344247 | 2008 | 11.472698775115 | 2007 | 11.559352031136 | 2006 | 11.835862402059 | 2005 | 12.176791530304 | 2004 | 12.424469752317 | 2003 | 12.646353159825 | 2002 | 12.866615270754 | 2001 | 13.122573997378 | 2000 | 13.305535353872 | 1999 | 13.689826837111 | 1998 | 14.34143295466 | 1997 | 14.166100380741 | 1996 | 14.429375011802 | 1995 | 14.558751902667 | 1994 | 14.41892290376 | 1993 | 14.970027228837 | 1992 | 15.34119418979 | 1991 | 15.29432105441 | 1990 | 15.164214836379 | 1989 | 15.198545723422 | 1988 | 16.30868819587 | 1987 | 15.800195300622 | 1986 | 16.140099387375 | 1985 | 16.71071938455 | 1984 | 16.890808569233 | 1983 | 16.765756052265 | 1982 | 16.125863432608 | 1981 | 16.145780400552 | 1980 | 16.302218880465 | 1979 | 16.506795263296 | 1978 | 16.67336394125 | 1977 | 16.763027114146 | 1976 | 17.169446585709 | 1975 | 17.522729355733 | 1974 | 17.725066840829 | 1973 | 17.796851268617 | 1972 | 18.316648031459 | 1971 | 18.255332966009 | 1970 | 18.694624238635 | 1969 | 18.980042147489 | 1968 | 19.073192756662 | 1967 | 19.409411770922 | 1966 | 19.588012794019 | 1965 | 19.520950636101 | 1964 | 19.595444484173 | 1963 | 19.975653676079 | 1962 | 20.181584886969 | 1961 | 20.427592008891 | 1960 | 20.649169223663 |
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