Year | Value | 2021 | 27.518700956982 | 2020 | 27.517804029861 | 2019 | 27.507156397279 | 2018 | 27.604466556197 | 2017 | 27.638457800223 | 2016 | 27.659016817399 | 2015 | 27.669296213527 | 2014 | 27.698783930249 | 2013 | 27.692115768463 | 2012 | 27.709487347136 | 2011 | 27.708697933392 | 2010 | 27.766791587995 | 2009 | 27.492296078005 | 2008 | 27.53250069464 | 2007 | 27.587608608167 | 2006 | 27.679195760673 | 2005 | 27.688085188754 | 2004 | 27.738933718924 | 2003 | 27.780542309103 | 2002 | 27.8555195277 | 2001 | 27.923196814878 | 2000 | 27.96161719008 | 1999 | 27.936272781666 | 1998 | 27.968248768054 | 1997 | 28.032917658918 | 1996 | 27.94058751868 | 1995 | 28.027893116621 | 1994 | 28.297139073044 | 1993 | 28.327178136857 | 1992 | 28.441140215958 | 1991 | 52.172619703413 | 1990 | 51.734129519864 | 1989 | 51.9743075601 | 1988 | 51.276909856113 | 1987 | 51.455390785096 | 1986 | 50.415353766829 | 1985 | 50.030848555627 | 1984 | 49.465658947183 | 1983 | 48.481810369522 | 1982 | 49.01284621995 | 1981 | 50.578410417998 | 1980 | 50.545358394112 | 1979 | 50.916642795761 | 1978 | 49.985677456316 | 1977 | 49.957032368949 | 1976 | 49.771941035189 | 1975 | 49.574730626005 | 1974 | 50.1156820836 | 1973 | 50.586122556905 | 1972 | 50.704008108763 | 1971 | 50.154242778133 | 1970 | 50.038560694533 | 1969 | 50.569596544962 | 1968 | 49.271753740387 | 1967 | 48.924707489589 | 1966 | 49.055813851002 | 1965 | 48.835467025098 | 1964 | 48.800211532953 | 1963 | 48.802415001212 | 1962 | 47.997047352533 | 1961 | 47.839499372012 |
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