Year | Value | 2021 | 11.069003512678 | 2020 | 11.094266397416 | 2019 | 11.365527017355 | 2018 | 11.687478798294 | 2017 | 11.966987202892 | 2016 | 12.452735365589 | 2015 | 12.559006525866 | 2014 | 12.63228229647 | 2013 | 12.506320357175 | 2012 | 12.657905941745 | 2011 | 12.548832440431 | 2010 | 12.689089282738 | 2009 | 12.684674128842 | 2008 | 12.713347018885 | 2007 | 12.322453794041 | 2006 | 12.017050039789 | 2005 | 11.80424349822 | 2004 | 11.841880542496 | 2003 | 11.625290881237 | 2002 | 11.543659748985 | 2001 | 11.552755194521 | 2000 | 11.670680017912 | 1999 | 11.650513929557 | 1998 | 11.928352378301 | 1997 | 12.106783258994 | 1996 | 12.327568704975 | 1995 | 12.552823712225 | 1994 | 12.869821278205 | 1993 | 13.213850741224 | 1992 | 13.796284230314 | 1991 | 14.395742736765 | 1990 | 14.88096272626 | 1989 | 15.257118334012 | 1988 | 15.861005639221 | 1987 | 16.167433044132 | 1986 | 16.308096746108 | 1985 | 16.221180071064 | 1984 | 16.353744652506 | 1983 | 16.497667038173 | 1982 | 16.396477734182 | 1981 | 16.382078100453 | 1980 | 16.595586698345 | 1979 | 16.669696658785 | 1978 | 16.842324864098 | 1977 | 16.923119995233 | 1976 | 17.147772297632 | 1975 | 17.256126426053 | 1974 | 17.536073100903 | 1973 | 17.458042692503 | 1972 | 17.781978058427 | 1971 | 18.10761854219 | 1970 | 18.060290588197 | 1969 | 18.369395527412 | 1968 | 18.697192280533 | 1967 | 19.053226622366 | 1966 | 19.21966631637 | 1965 | 19.682845436698 | 1964 | 20.393140554352 | 1963 | 20.85363064961 | 1962 | 21.270608800919 | 1961 | 21.773241271913 | 1960 | 22.084201207019 |
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