Year | Value | 2021 | 34.421155709292 | 2020 | 34.456675892318 | 2019 | 34.46113872461 | 2018 | 34.516057006069 | 2017 | 34.533805908886 | 2016 | 34.571716911452 | 2015 | 34.578955143136 | 2014 | 34.56046191139 | 2013 | 34.600051793951 | 2012 | 34.554026892527 | 2011 | 34.551358341543 | 2010 | 34.570187319753 | 2009 | 34.439925689898 | 2008 | 34.428752932591 | 2007 | 34.391164331611 | 2006 | 34.394066166001 | 2005 | 34.37223936327 | 2004 | 34.368376644036 | 2003 | 34.394338736311 | 2002 | 34.743435338459 | 2001 | 34.762111752214 | 2000 | 34.859129889264 | 1999 | 34.825234085143 | 1998 | 34.815896390671 | 1997 | 34.813279926557 | 1996 | 34.522192757869 | 1995 | 34.539138834115 | 1994 | 34.729473886112 | 1993 | 34.686453507487 | 1992 | 34.774015470971 | 1991 | 43.387921650376 | 1990 | 43.202071872143 | 1989 | 43.011406832499 | 1988 | 42.806723427913 | 1987 | 42.615961031122 | 1986 | 42.4185074648 | 1985 | 42.21825650752 | 1984 | 41.649543286726 | 1983 | 41.10185633537 | 1982 | 40.573564372001 | 1981 | 40.089353290035 | 1980 | 39.778458438169 | 1979 | 39.357759447221 | 1978 | 39.015321456384 | 1977 | 38.548387687194 | 1976 | 38.047410190622 | 1975 | 38.156420090465 | 1974 | 37.788854769087 | 1973 | 37.325005352112 | 1972 | 36.890790100931 | 1971 | 36.50686392394 | 1970 | 36.069648011086 | 1969 | 35.69615028114 | 1968 | 35.337859559133 | 1967 | 34.999790204824 | 1966 | 34.678536458928 | 1965 | 34.345927221135 | 1964 | 33.968103147296 | 1963 | 33.648488688026 | 1962 | 33.311057282701 | 1961 | 32.979731210647 |
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