Year | Value | 2022 | 7.308 | 2021 | 7.874 | 2020 | 8.01 | 2019 | 8.415 | 2018 | 9.018 | 2017 | 9.41 | 2016 | 10.057 | 2015 | 10.354 | 2014 | 10.273 | 2013 | 9.913 | 2012 | 9.841 | 2011 | 9.228 | 2010 | 9.279 | 2009 | 9.122 | 2008 | 7.386 | 2007 | 8.009 | 2006 | 8.833 | 2005 | 8.882 | 2004 | 8.914 | 2003 | 8.307 | 2002 | 8.702 | 2001 | 8.61 | 2000 | 10.218 | 1999 | 11.981 | 1998 | 12.074 | 1997 | 12.566 | 1996 | 12.367 | 1995 | 11.834 | 1994 | 12.593 | 1993 | 11.321 | 1992 | 10.203 | 1991 | 9.134 | 1990 | 11.05 | 1989 | 9.618 | 1988 | 10.18 | 1987 | 10.735 | 1986 | 10.23 | 1985 | 10.259 | 1984 | 9.533 | 1983 | 7.918 | 1982 | 8.2 | 1981 | 7.54 | 1980 | 6.42 | 1979 | 6.03 | 1978 | 5.27 | 1977 | 5.01 | 1976 | 4.47 | 1975 | 4.08 | 1974 | 2.86 | 1973 | 2.69 | 1972 | 2.77 | 1971 | 2.67 | 1970 | 2.42 |
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