Year | Value | 2023 | 10.147 | 2022 | 10.286 | 2021 | 15.253 | 2020 | 10.403 | 2019 | 10.047 | 2018 | 9.866 | 2017 | 9.91 | 2016 | 9.44 | 2015 | 9.123 | 2014 | 8.884 | 2013 | 8.516 | 2012 | 8.245 | 2011 | 8.165 | 2010 | 8.151 | 2009 | 8.212 | 2008 | 8.002 | 2007 | 7.84 | 2006 | 7.701 | 2005 | 7.364 | 2004 | 7.324 | 2003 | 7.103 | 2002 | 7.326 | 2001 | 7.28 | 2000 | 7.354 | 1999 | 7.237 | 1998 | 7.214 | 1997 | 7.262 | 1996 | 7.334 | 1995 | 7.373 | 1994 | 7.353 | 1993 | 7.38 | 1992 | 7.255 | 1991 | 7.17 | 1990 | 6.982 | 1989 | 6.942 | 1988 | 6.789 | 1987 | 6.733 | 1986 | 6.647 | 1985 | 6.581 | 1984 | 6.434 | 1983 | 6.303 | 1982 | 6.256 | 1981 | 6.377 | 1980 | 6.314 | 1979 | 6.251 | 1978 | 6.188 | 1977 | 6.215 | 1976 | 6.27 | 1975 | 6.355 |
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