Year | Value | 2021 | 20.828985456128 | 2020 | 21.284368912072 | 2019 | 21.797963511541 | 2018 | 22.70318222191 | 2017 | 23.426871084108 | 2016 | 23.965657167583 | 2015 | 24.998114476058 | 2014 | 25.511902763091 | 2013 | 25.725201652348 | 2012 | 25.69245172471 | 2011 | 25.466768041292 | 2010 | 25.245647819707 | 2009 | 24.925528276286 | 2008 | 24.807828781549 | 2007 | 24.667396932478 | 2006 | 24.445485636745 | 2005 | 24.361344737278 | 2004 | 24.33236594238 | 2003 | 24.370956827864 | 2002 | 24.40670794874 | 2001 | 24.646233131673 | 2000 | 24.844638252829 | 1999 | 25.158858033074 | 1998 | 25.555889461041 | 1997 | 26.063145578599 | 1996 | 26.817002468787 | 1995 | 27.99294971944 | 1994 | 29.295834732939 | 1993 | 30.682103796305 | 1992 | 31.871021777274 | 1991 | 32.812153068616 | 1990 | 33.740658365502 | 1989 | 34.777660504416 | 1988 | 36.006597061214 | 1987 | 37.17109645712 | 1986 | 38.328271185328 | 1985 | 39.364896243628 | 1984 | 40.169508467731 | 1983 | 40.871763394317 | 1982 | 41.368697344101 | 1981 | 41.604983318139 | 1980 | 42.053746231213 | 1979 | 42.327563061806 | 1978 | 42.208989826697 | 1977 | 42.274755192616 | 1976 | 42.472598988232 | 1975 | 42.520814548035 | 1974 | 42.615201977663 | 1973 | 42.812948811946 | 1972 | 43.277126584443 | 1971 | 43.803704169724 | 1970 | 44.26592851865 | 1969 | 44.758913951971 | 1968 | 45.142356755948 | 1967 | 45.597003706137 | 1966 | 45.980013174431 | 1965 | 46.333842464088 | 1964 | 46.81611749163 | 1963 | 47.274199641512 | 1962 | 47.75163188975 | 1961 | 47.552571738537 | 1960 | 47.808689074049 |
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