Year | Value | 2021 | 25.380477046234 | 2020 | 25.380477046234 | 2019 | 25.367058759462 | 2018 | 25.38976746719 | 2017 | 25.423133474922 | 2016 | 25.402167401841 | 2015 | 25.404345695148 | 2014 | 25.382562762076 | 2013 | 25.388008495344 | 2012 | 25.404345695148 | 2011 | 25.388008495344 | 2010 | 25.524151827044 | 2009 | 25.430189501198 | 2008 | 25.588107166195 | 2007 | 25.789588324984 | 2006 | 25.431574361488 | 2005 | 25.467124257776 | 2004 | 25.913820341014 | 2003 | 25.192003921782 | 2002 | 24.991838067254 | 2001 | 25.220372184133 | 2000 | 24.714332353901 | 1999 | 25.579497224943 | 1998 | 25.62302753292 | 1997 | 25.960387419741 | 1996 | 25.786266187833 | 1995 | 26.11274349766 | 1994 | 26.183480248123 | 1993 | 25.960387419741 | 1992 | 25.933180977255 | 1991 | 26.139949940146 | 1990 | 26.580694308412 | 1989 | 26.107302209163 | 1988 | 26.183480248123 | 1987 | 27.097616715638 | 1986 | 27.277179236043 | 1985 | 27.413211448471 | 1984 | 27.772336489281 | 1983 | 27.652628142344 | 1982 | 28.77353357275 | 1981 | 28.702796822287 | 1980 | 28.457938839917 | 1979 | 28.457938839917 | 1978 | 28.017194471651 | 1977 | 27.658069430841 | 1976 | 28.621177494831 | 1975 | 27.88660354772 | 1974 | 30.917401240614 | 1973 | 30.199151158994 | 1972 | 31.07519860703 | 1971 | 30.726956143215 | 1970 | 30.748721297203 | 1969 | 30.607247796278 | 1968 | 30.346065948417 | 1967 | 31.973011209054 | 1966 | 31.956687343563 | 1965 | 34.50865164871 | 1964 | 34.878659266514 | 1963 | 34.280117531832 | 1962 | 33.73598868212 | 1961 | 33.442159103276 |
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