Year | Value | 2021 | 51.946881295847 | 2020 | 51.946881295847 | 2019 | 52.256692777791 | 2018 | 52.29329810742 | 2017 | 52.433627181579 | 2016 | 52.575516532748 | 2015 | 52.607805084774 | 2014 | 52.624622038955 | 2013 | 52.617558918199 | 2012 | 52.652538182895 | 2011 | 52.798173006098 | 2010 | 52.808263178606 | 2009 | 53.11601344011 | 2008 | 53.139893515046 | 2007 | 53.148974670304 | 2006 | 53.364231683814 | 2005 | 53.627248847198 | 2004 | 53.706961210014 | 2003 | 53.74664922188 | 2002 | 53.959551861805 | 2001 | 53.923563579859 | 2000 | 54.127048725443 | 1999 | 54.142183984206 | 1998 | 54.288155146492 | 1997 | 54.352732250546 | 1996 | 54.159000938386 | 1995 | 54.456997366465 | 1994 | 54.663509563802 | 1993 | 54.684026247902 | 1992 | 54.724386937935 | 1991 | 54.884484341734 | 1990 | 54.977650267894 | 1989 | 54.983368032315 | 1988 | 54.77887386948 | 1987 | 54.892220140657 | 1986 | 54.960833313714 | 1985 | 55.004893733666 | 1984 | 55.031128182188 | 1983 | 54.733131754109 | 1982 | 54.906010043085 | 1981 | 54.793672789159 | 1980 | 54.77416512231 | 1979 | 54.97260518164 | 1978 | 54.9036556695 | 1977 | 54.506775550839 | 1976 | 54.506102872672 | 1975 | 54.432444613361 | 1974 | 54.319098342185 | 1973 | 54.165391380975 | 1972 | 53.876812447237 | 1971 | 53.732186641284 | 1970 | 54.002603264507 | 1969 | 53.806181239679 | 1968 | 53.837460774454 | 1967 | 53.740258779291 | 1966 | 53.340015269794 | 1965 | 53.214224452524 | 1964 | 53.051436336057 | 1963 | 52.963315496151 | 1962 | 52.704334401771 | 1961 | 52.403647261023 |
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