Year | Value | 2022 | 50.234567419524 | 2021 | 50.216312536335 | 2020 | 50.197335621877 | 2019 | 50.182491729106 | 2018 | 50.168452087526 | 2017 | 50.154798370826 | 2016 | 50.14199106693 | 2015 | 50.129250963247 | 2014 | 50.116881051062 | 2013 | 50.105715224513 | 2012 | 50.095115942561 | 2011 | 50.084214082826 | 2010 | 50.07522020009 | 2009 | 50.067639364552 | 2008 | 50.078036940509 | 2007 | 50.089443536588 | 2006 | 50.083278098108 | 2005 | 50.074055299639 | 2004 | 50.062038369405 | 2003 | 50.048106212277 | 2002 | 50.033418509332 | 2001 | 50.018313662644 | 2000 | 50.002382608129 | 1999 | 49.985868630527 | 1998 | 49.96708500515 | 1997 | 49.948862966258 | 1996 | 49.932426938131 | 1995 | 49.918962571664 | 1994 | 49.907762950937 | 1993 | 49.897557455194 | 1992 | 49.890616168224 | 1991 | 49.885541076859 | 1990 | 49.880984957613 | 1989 | 49.877140506929 | 1988 | 49.87252326898 | 1987 | 49.868573548346 | 1986 | 49.86462381635 | 1985 | 49.862487534238 | 1984 | 49.861943518663 | 1983 | 49.861580743729 | 1982 | 49.861818000537 | 1981 | 49.863075737865 | 1980 | 49.864197103304 | 1979 | 49.863461087834 | 1978 | 49.864033920013 | 1977 | 49.864587088069 | 1976 | 49.865136891945 | 1975 | 49.868133284841 | 1974 | 49.870428600008 | 1973 | 49.870068446961 | 1972 | 49.871915924198 | 1971 | 49.874620960315 | 1970 | 49.875216756184 | 1969 | 49.875535827238 | 1968 | 49.875278906621 | 1967 | 49.876224590782 | 1966 | 49.879865799247 | 1965 | 49.882467396592 | 1964 | 49.884332249915 | 1963 | 49.889122196168 | 1962 | 49.895265149504 | 1961 | 49.900732370408 | 1960 | 49.907008048591 |
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