Year | Value | 2021 | 9.1065164428426 | 2020 | 8.8275228480769 | 2019 | 8.6717704249384 | 2018 | 8.8538591330197 | 2017 | 9.0441123509028 | 2016 | 9.2457809170401 | 2015 | 9.5008423506431 | 2014 | 9.7198829108433 | 2013 | 9.9735197710315 | 2012 | 10.262165012973 | 2011 | 10.59140016236 | 2010 | 10.973599646133 | 2009 | 11.329073546942 | 2008 | 11.763031437362 | 2007 | 12.123299712334 | 2006 | 12.505785800306 | 2005 | 12.94059275853 | 2004 | 13.3224027883 | 2003 | 13.65778081066 | 2002 | 13.993012520734 | 2001 | 14.273980021565 | 2000 | 14.493219627976 | 1999 | 14.914136806536 | 1998 | 15.582919594474 | 1997 | 15.368701786539 | 1996 | 15.561245006722 | 1995 | 15.613494548881 | 1994 | 16.539599084397 | 1993 | 16.127924300324 | 1992 | 16.44885088178 | 1991 | 16.33747133639 | 1990 | 16.232791738885 | 1989 | 16.266121398327 | 1988 | 17.283410390831 | 1987 | 16.857481316045 | 1986 | 17.19252297884 | 1985 | 17.537624736864 | 1984 | 17.789938741088 | 1983 | 17.867640163435 | 1982 | 17.13720680976 | 1981 | 17.3503166695 | 1980 | 17.598308594393 | 1979 | 17.842586395113 | 1978 | 18.175609558809 | 1977 | 18.406840130613 | 1976 | 18.748420246654 | 1975 | 19.316150442538 | 1974 | 19.626095637235 | 1973 | 19.772413623885 | 1972 | 20.389185993076 | 1971 | 20.434690291078 | 1970 | 20.863863766617 | 1969 | 21.232866066302 | 1968 | 21.417683509927 | 1967 | 21.792068753141 | 1966 | 22.002401990247 | 1965 | 21.944502512562 | 1964 | 22.059329999347 | 1963 | 22.418489592414 | 1962 | 22.619673840497 | 1961 | 22.984020938597 | 1960 | 23.241669936758 |
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