Year | Value | 2022 | 27.968 | 2021 | 27.726 | 2020 | 27.506 | 2019 | 27.309 | 2018 | 27.134 | 2017 | 26.982 | 2016 | 26.851 | 2015 | 26.742 | 2014 | 26.655 | 2013 | 26.589 | 2012 | 26.545 | 2011 | 26.521 | 2010 | 26.52 | 2009 | 26.518 | 2008 | 26.516 | 2007 | 26.514 | 2006 | 26.512 | 2005 | 26.51 | 2004 | 26.508 | 2003 | 26.507 | 2002 | 26.505 | 2001 | 26.503 | 2000 | 26.501 | 1999 | 26.76 | 1998 | 27.28 | 1997 | 27.806 | 1996 | 28.338 | 1995 | 28.877 | 1994 | 29.421 | 1993 | 29.972 | 1992 | 30.527 | 1991 | 31.09 | 1990 | 31.658 | 1989 | 32.231 | 1988 | 32.61 | 1987 | 32.818 | 1986 | 33.026 | 1985 | 33.235 | 1984 | 33.445 | 1983 | 33.655 | 1982 | 33.866 | 1981 | 34.078 | 1980 | 34.289 | 1979 | 34.502 | 1978 | 34.743 | 1977 | 35.006 | 1976 | 35.27 | 1975 | 35.536 | 1974 | 35.802 | 1973 | 36.07 | 1972 | 36.337 | 1971 | 36.607 | 1970 | 36.876 | 1969 | 36.777 | 1968 | 36.368 | 1967 | 35.96 | 1966 | 35.555 | 1965 | 35.152 | 1964 | 34.751 | 1963 | 34.351 | 1962 | 33.955 | 1961 | 33.56 | 1960 | 33.168 |
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