Year | Value | 2021 | 32.832355467942 | 2020 | 32.838864426826 | 2019 | 32.697683362065 | 2018 | 32.682318984856 | 2017 | 32.731566820392 | 2016 | 32.915377741394 | 2015 | 33.046150574296 | 2014 | 33.022739739428 | 2013 | 33.221362883476 | 2012 | 33.225029467251 | 2011 | 33.216686740018 | 2010 | 33.289602419087 | 2009 | 33.214822840956 | 2008 | 33.347842020983 | 2007 | 33.612655893209 | 2006 | 33.55444658212 | 2005 | 33.567715824014 | 2004 | 33.511918031829 | 2003 | 33.433539732983 | 2002 | 33.426238869936 | 2001 | 33.391021954207 | 2000 | 33.52209816371 | 1999 | 33.542995572079 | 1998 | 33.512045080476 | 1997 | 33.395745480719 | 1996 | 33.353972738695 | 1995 | 33.316393634736 | 1994 | 33.365931687677 | 1993 | 33.425678147831 | 1992 | 33.454219282291 | 1991 | 33.521663929076 | 1990 | 33.520895835908 | 1989 | 33.405065606893 | 1988 | 33.410740562484 | 1987 | 33.425291207872 | 1986 | 33.433632882014 | 1985 | 33.442890562444 | 1984 | 33.313355812062 | 1983 | 33.129418955224 | 1982 | 32.880179341085 | 1981 | 32.758007501913 | 1980 | 32.605753999376 | 1979 | 32.310410144276 | 1978 | 32.017089256242 | 1977 | 31.717003814323 | 1976 | 31.383822739334 | 1975 | 31.064931032138 | 1974 | 30.813009196782 | 1973 | 30.555965096515 | 1972 | 30.324941210074 | 1971 | 30.059032627908 | 1970 | 29.763984821729 | 1969 | 29.554785151001 | 1968 | 29.428174194692 | 1967 | 29.243595688979 | 1966 | 29.103094584587 | 1965 | 28.939230953147 | 1964 | 28.758212738098 | 1963 | 28.59263916424 | 1962 | 28.435439795184 | 1961 | 28.259029900023 |
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