Year | Value | 2022 | 28.646 | 2021 | 28.881 | 2020 | 29.107 | 2019 | 29.322 | 2018 | 29.527 | 2017 | 29.722 | 2016 | 29.906 | 2015 | 30.079 | 2014 | 30.242 | 2013 | 30.405 | 2012 | 30.568 | 2011 | 30.732 | 2010 | 30.897 | 2009 | 31.02 | 2008 | 31.073 | 2007 | 31.127 | 2006 | 31.181 | 2005 | 31.234 | 2004 | 31.288 | 2003 | 31.342 | 2002 | 31.396 | 2001 | 31.45 | 2000 | 31.504 | 1999 | 31.558 | 1998 | 31.612 | 1997 | 31.595 | 1996 | 31.407 | 1995 | 31.22 | 1994 | 31.034 | 1993 | 30.848 | 1992 | 30.663 | 1991 | 30.478 | 1990 | 30.294 | 1989 | 30.111 | 1988 | 29.928 | 1987 | 29.983 | 1986 | 30.604 | 1985 | 31.233 | 1984 | 31.868 | 1983 | 32.512 | 1982 | 33.161 | 1981 | 33.817 | 1980 | 34.479 | 1979 | 35.148 | 1978 | 35.822 | 1977 | 36.596 | 1976 | 37.602 | 1975 | 38.621 | 1974 | 39.649 | 1973 | 40.687 | 1972 | 41.731 | 1971 | 42.786 | 1970 | 43.846 | 1969 | 44.911 | 1968 | 45.98 | 1967 | 47.055 | 1966 | 48.132 | 1965 | 49.349 | 1964 | 50.907 | 1963 | 52.468 | 1962 | 54.022 | 1961 | 55.568 | 1960 | 57.101 |
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