Year | Value | 2021 | 24.831500532104 | 2020 | 24.831500532104 | 2019 | 24.831500532104 | 2018 | 24.831500532104 | 2017 | 24.831500532104 | 2016 | 24.831500532104 | 2015 | 23.944661227386 | 2014 | 23.944661227386 | 2013 | 23.944661227386 | 2012 | 23.057821922668 | 2011 | 22.17098261795 | 2010 | 22.17098261795 | 2009 | 22.17098261795 | 2008 | 22.17098261795 | 2007 | 22.17098261795 | 2006 | 22.17098261795 | 2005 | 23.536715147215 | 2004 | 23.501241575027 | 2003 | 23.501241575027 | 2002 | 22.614402270309 | 2001 | 21.727562965591 | 2000 | 21.106775452288 | 1999 | 20.397304008514 | 1998 | 19.953884356155 | 1997 | 18.623625399078 | 1996 | 17.293366442001 | 1995 | 15.874423554452 | 1994 | 15.076268180206 | 1993 | 14.632848527847 | 1992 | 14.455480666903 | 1991 | 14.366796736431 | 1990 | 14.322454771196 | 1989 | 14.366796736431 | 1988 | 14.27811280596 | 1987 | 14.189428875488 | 1986 | 14.100744945016 | 1985 | 14.012061014544 | 1984 | 13.923377084072 | 1983 | 13.834693153601 | 1982 | 13.746009223129 | 1981 | 13.568641362185 | 1980 | 13.30258957077 | 1979 | 13.036537779354 | 1978 | 12.859169918411 | 1977 | 12.681802057467 | 1976 | 12.415750266052 | 1975 | 12.149698474636 | 1974 | 11.794962752749 | 1973 | 11.528910961334 | 1972 | 11.35154310039 | 1971 | 11.085491308975 | 1970 | 10.642071656616 | 1969 | 10.464703795672 | 1968 | 9.7552323518978 | 1967 | 9.4891805604824 | 1966 | 9.1344448385953 | 1965 | 8.8683930471799 | 1964 | 8.6910251862362 | 1963 | 8.5136573252927 | 1962 | 8.3362894643491 | 1961 | 8.1589216034055 |
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