Year | Value | 2022 | 31.771 | 2021 | 31.448 | 2020 | 31.141 | 2019 | 30.852 | 2018 | 30.579 | 2017 | 30.322 | 2016 | 30.082 | 2015 | 29.858 | 2014 | 29.65 | 2013 | 29.457 | 2012 | 29.266 | 2011 | 29.075 | 2010 | 28.885 | 2009 | 28.695 | 2008 | 28.507 | 2007 | 28.319 | 2006 | 28.132 | 2005 | 27.946 | 2004 | 27.76 | 2003 | 27.575 | 2002 | 27.391 | 2001 | 27.208 | 2000 | 27.025 | 1999 | 26.843 | 1998 | 26.663 | 1997 | 26.482 | 1996 | 26.303 | 1995 | 26.124 | 1994 | 25.946 | 1993 | 25.769 | 1992 | 25.593 | 1991 | 25.418 | 1990 | 25.243 | 1989 | 25.069 | 1988 | 24.896 | 1987 | 24.724 | 1986 | 24.552 | 1985 | 24.381 | 1984 | 24.212 | 1983 | 24.042 | 1982 | 23.993 | 1981 | 23.982 | 1980 | 23.973 | 1979 | 23.962 | 1978 | 23.952 | 1977 | 23.942 | 1976 | 23.933 | 1975 | 23.922 | 1974 | 23.913 | 1973 | 23.903 | 1972 | 23.606 | 1971 | 23.215 | 1970 | 22.83 | 1969 | 22.449 | 1968 | 22.073 | 1967 | 21.701 | 1966 | 21.334 | 1965 | 20.971 | 1964 | 20.613 | 1963 | 20.259 | 1962 | 19.91 | 1961 | 19.566 | 1960 | 19.226 |
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