Year | Value | 2021 | 51.7 | 2020 | 51.7 | 2019 | 51.7 | 2018 | 51.8 | 2017 | 51.8 | 2016 | 52 | 2015 | 52.2 | 2014 | 52.4 | 2013 | 53.4 | 2012 | 54.7 | 2011 | 56 | 2010 | 57.3 | 2009 | 58.6 | 2008 | 59.9 | 2007 | 61.2 | 2006 | 62.5 | 2005 | 63.8 | 2004 | 65.1 | 2003 | 66.4 | 2002 | 67.7 | 2001 | 69 | 2000 | 70 | 1999 | 70 | 1998 | 70 | 1997 | 70 | 1996 | 70 | 1995 | 70 | 1994 | 70 | 1993 | 70 | 1992 | 70 | 1991 | 70 | 1990 | 70 | 1989 | 80 | 1988 | 80 | 1987 | 80 | 1986 | 80 | 1985 | 90 | 1984 | 90 | 1983 | 90 | 1982 | 90 | 1981 | 90 | 1980 | 90 | 1979 | 90 | 1978 | 90 | 1977 | 90 | 1976 | 90 | 1975 | 90 | 1974 | 90 | 1973 | 90 | 1972 | 90 | 1971 | 90 | 1970 | 90 | 1969 | 90 | 1968 | 90 | 1967 | 90 | 1966 | 90 | 1965 | 90 | 1964 | 90 | 1963 | 90 | 1962 | 90 | 1961 | 90 |
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