Year | Value | 2021 | 32.793955697763 | 2020 | 32.793955697763 | 2019 | 32.992041011256 | 2018 | 33.104133450947 | 2017 | 33.721360515891 | 2016 | 33.523297117926 | 2015 | 33.747536786124 | 2014 | 33.481628396678 | 2013 | 33.431587944269 | 2012 | 33.387756891063 | 2011 | 33.374424945713 | 2010 | 33.422456474851 | 2009 | 33.341186397033 | 2008 | 33.364015070577 | 2007 | 33.395975213539 | 2006 | 33.492403530591 | 2005 | 33.562898474497 | 2004 | 33.544753427435 | 2003 | 33.502291614571 | 2002 | 33.551145339292 | 2001 | 33.504393069707 | 2000 | 33.519916284217 | 1999 | 33.517603357404 | 1998 | 33.45350149571 | 1997 | 33.366023456533 | 1996 | 33.247133678862 | 1995 | 33.18887586154 | 1994 | 33.048436170252 | 1993 | 32.934477305019 | 1992 | 32.593148588481 | 1991 | 32.564658872173 | 1990 | 32.479737602408 | 1989 | 32.342950438851 | 1988 | 32.531238243426 | 1987 | 33.177735651958 | 1986 | 32.869097058619 | 1985 | 32.732127268676 | 1984 | 32.523933187963 | 1983 | 32.268256246736 | 1982 | 32.235383497149 | 1981 | 32.007100513911 | 1980 | 31.908482265152 | 1979 | 31.778817530672 | 1978 | 31.691156865108 | 1977 | 31.530445644909 | 1976 | 31.285726286877 | 1975 | 31.65463158779 | 1974 | 31.554187075165 | 1973 | 31.22180705157 | 1972 | 31.095794844822 | 1971 | 31.148756496934 | 1970 | 31.808037752527 | 1969 | 32.078324804681 | 1968 | 32.103892498804 | 1967 | 33.01154564016 | 1966 | 33.718309756267 | 1965 | 34.326455623614 | 1964 | 34.8414620338 | 1963 | 35.529963511248 | 1962 | 35.666933301191 | 1961 | 35.805729355 |
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