Year | Value | 2021 | 12.328911016541 | 2020 | 12.313114742704 | 2019 | 12.334111421694 | 2018 | 12.330586412612 | 2017 | 12.359486105979 | 2016 | 12.367393108782 | 2015 | 12.38574450713 | 2014 | 12.400760153205 | 2013 | 12.398852703251 | 2012 | 12.414502725892 | 2011 | 12.399327071273 | 2010 | 12.419562686522 | 2009 | 12.459027454377 | 2008 | 12.472694571248 | 2007 | 12.467968512239 | 2006 | 12.561920144219 | 2005 | 12.557753841437 | 2004 | 12.597546772856 | 2003 | 12.613658748591 | 2002 | 12.713748692227 | 2001 | 12.815077284379 | 2000 | 12.97536541017 | 1999 | 13.104662171056 | 1998 | 13.181755889548 | 1997 | 13.295307358259 | 1996 | 13.270253191795 | 1995 | 13.377516272339 | 1994 | 13.461656074877 | 1993 | 13.533617922745 | 1992 | 13.531187877875 | 1991 | 26.296982666423 | 1990 | 26.437983073641 | 1989 | 26.529680275571 | 1988 | 26.699954536249 | 1987 | 26.840764434019 | 1986 | 26.726036805578 | 1985 | 26.73271842164 | 1984 | 26.710450244892 | 1983 | 26.49152478733 | 1982 | 26.68646416072 | 1981 | 26.932219703044 | 1980 | 26.92478070719 | 1979 | 27.004441893621 | 1978 | 26.918916473358 | 1977 | 26.85690690066 | 1976 | 26.809614644099 | 1975 | 26.869396939654 | 1974 | 27.002936595572 | 1973 | 27.0890397244 | 1972 | 27.216689986876 | 1971 | 27.191735653986 | 1970 | 27.611821110963 | 1969 | 27.899645538987 | 1968 | 27.737725029879 | 1967 | 27.823386671434 | 1966 | 27.955358037723 | 1965 | 28.132180123719 | 1964 | 28.275139490273 | 1963 | 28.446491873103 | 1962 | 28.403640947635 | 1961 | 28.43305513683 |
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