Year | Value | 2022 | 16.894 | 2021 | 16.751 | 2020 | 16.626 | 2019 | 16.517 | 2018 | 16.425 | 2017 | 16.35 | 2016 | 16.29 | 2015 | 16.247 | 2014 | 16.219 | 2013 | 16.208 | 2012 | 16.212 | 2011 | 16.216 | 2010 | 16.221 | 2009 | 16.225 | 2008 | 16.229 | 2007 | 16.234 | 2006 | 16.238 | 2005 | 16.242 | 2004 | 16.247 | 2003 | 16.251 | 2002 | 16.255 | 2001 | 16.26 | 2000 | 16.186 | 1999 | 16.103 | 1998 | 16.02 | 1997 | 15.937 | 1996 | 15.855 | 1995 | 15.773 | 1994 | 15.691 | 1993 | 15.61 | 1992 | 15.529 | 1991 | 15.449 | 1990 | 15.368 | 1989 | 15.289 | 1988 | 15.209 | 1987 | 14.993 | 1986 | 14.763 | 1985 | 14.536 | 1984 | 14.312 | 1983 | 14.09 | 1982 | 13.871 | 1981 | 13.656 | 1980 | 13.443 | 1979 | 13.233 | 1978 | 13.025 | 1977 | 12.648 | 1976 | 12.021 | 1975 | 11.419 | 1974 | 10.845 | 1973 | 10.296 | 1972 | 9.772 | 1971 | 9.271 | 1970 | 8.794 | 1969 | 8.339 | 1968 | 7.906 | 1967 | 7.493 | 1966 | 7.1 | 1965 | 6.809 | 1964 | 6.529 | 1963 | 6.259 | 1962 | 6 | 1961 | 5.896 | 1960 | 5.793 |
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