Year | Value | 2021 | 1.52 | 2020 | 1.46 | 2019 | 1.48 | 2018 | 1.52 | 2017 | 1.52 | 2016 | 1.54 | 2015 | 1.54 | 2014 | 1.54 | 2013 | 1.52 | 2012 | 1.52 | 2011 | 1.52 | 2010 | 1.52 | 2009 | 1.5 | 2008 | 1.48 | 2007 | 1.46 | 2006 | 1.44 | 2005 | 1.42 | 2004 | 1.42 | 2003 | 1.39 | 2002 | 1.39 | 2001 | 1.38 | 2000 | 1.5 | 1999 | 1.48 | 1998 | 1.47 | 1997 | 1.48 | 1996 | 1.5 | 1995 | 1.48 | 1994 | 1.49 | 1993 | 1.51 | 1992 | 1.58 | 1991 | 1.58 | 1990 | 1.58 | 1989 | 1.56 | 1988 | 1.57 | 1987 | 1.52 | 1986 | 1.53 | 1985 | 1.52 | 1984 | 1.53 | 1983 | 1.52 | 1982 | 1.56 | 1981 | 1.55 | 1980 | 1.55 | 1979 | 1.52 | 1978 | 1.51 | 1977 | 1.53 | 1976 | 1.55 | 1975 | 1.61 | 1974 | 1.73 | 1973 | 1.81 | 1972 | 1.91 | 1971 | 2.04 | 1970 | 2.1 | 1969 | 2.19 | 1968 | 2.29 | 1967 | 2.39 | 1966 | 2.5 | 1965 | 2.59 | 1964 | 2.66 | 1963 | 2.65 | 1962 | 2.58 | 1961 | 2.52 | 1960 | 2.44 |
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