Year | Value | 2022 | 30.391 | 2021 | 30.585 | 2020 | 30.771 | 2019 | 30.949 | 2018 | 31.12 | 2017 | 31.283 | 2016 | 31.437 | 2015 | 31.584 | 2014 | 31.731 | 2013 | 31.878 | 2012 | 32.026 | 2011 | 32.035 | 2010 | 31.906 | 2009 | 31.777 | 2008 | 31.649 | 2007 | 31.521 | 2006 | 31.393 | 2005 | 31.265 | 2004 | 31.138 | 2003 | 31.011 | 2002 | 30.884 | 2001 | 30.758 | 2000 | 30.632 | 1999 | 30.457 | 1998 | 30.267 | 1997 | 30.077 | 1996 | 29.889 | 1995 | 29.7 | 1994 | 29.513 | 1993 | 29.326 | 1992 | 29.14 | 1991 | 28.954 | 1990 | 28.769 | 1989 | 28.585 | 1988 | 28.61 | 1987 | 28.817 | 1986 | 29.025 | 1985 | 29.233 | 1984 | 29.442 | 1983 | 29.653 | 1982 | 29.864 | 1981 | 30.076 | 1980 | 30.289 | 1979 | 30.503 | 1978 | 30.876 | 1977 | 31.383 | 1976 | 31.894 | 1975 | 32.411 | 1974 | 32.931 | 1973 | 33.455 | 1972 | 33.983 | 1971 | 34.517 | 1970 | 35.053 | 1969 | 35.693 | 1968 | 36.423 | 1967 | 37.161 | 1966 | 37.903 | 1965 | 38.652 | 1964 | 39.404 | 1963 | 40.164 | 1962 | 40.928 | 1961 | 41.696 | 1960 | 42.467 |
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