Year | Value | 2022 | 23.125 | 2021 | 23.104 | 2020 | 23.099 | 2019 | 23.107 | 2018 | 23.131 | 2017 | 23.169 | 2016 | 23.222 | 2015 | 23.275 | 2014 | 23.328 | 2013 | 23.382 | 2012 | 23.435 | 2011 | 23.443 | 2010 | 23.389 | 2009 | 23.335 | 2008 | 23.281 | 2007 | 23.227 | 2006 | 23.184 | 2005 | 23.155 | 2004 | 23.127 | 2003 | 23.098 | 2002 | 23.069 | 2001 | 23.041 | 2000 | 23.012 | 1999 | 22.984 | 1998 | 22.955 | 1997 | 22.927 | 1996 | 22.897 | 1995 | 22.864 | 1994 | 22.832 | 1993 | 22.8 | 1992 | 22.768 | 1991 | 22.736 | 1990 | 22.704 | 1989 | 22.672 | 1988 | 22.641 | 1987 | 22.609 | 1986 | 22.496 | 1985 | 22.268 | 1984 | 22.042 | 1983 | 21.817 | 1982 | 21.594 | 1981 | 21.373 | 1980 | 21.154 | 1979 | 20.935 | 1978 | 20.719 | 1977 | 20.504 | 1976 | 20.367 | 1975 | 20.337 | 1974 | 20.307 | 1973 | 20.277 | 1972 | 20.247 | 1971 | 20.217 | 1970 | 20.187 | 1969 | 20.157 | 1968 | 20.127 | 1967 | 20.097 | 1966 | 19.908 | 1965 | 19.499 | 1964 | 19.098 | 1963 | 18.701 | 1962 | 18.312 | 1961 | 17.929 | 1960 | 17.552 |
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