Year | Value | 2022 | 5.558 | 2021 | 6.264 | 2020 | 5.555 | 2019 | 5.36 | 2018 | 5.948 | 2017 | 7.086 | 2016 | 7.83 | 2015 | 8.482 | 2014 | 8.523 | 2013 | 8.425 | 2012 | 7.542 | 2011 | 7.14 | 2010 | 8.293 | 2009 | 7.908 | 2008 | 6.976 | 2007 | 7.459 | 2006 | 8.246 | 2005 | 8.44 | 2004 | 7.363 | 2003 | 7.68 | 2002 | 6.91 | 2001 | 6.178 | 2000 | 6.586 | 1999 | 8.649 | 1998 | 9.323 | 1997 | 8.95 | 1996 | 9.483 | 1995 | 9.337 | 1994 | 9.645 | 1993 | 8.078 | 1992 | 6.702 | 1991 | 6.984 | 1990 | 7.25 | 1989 | 8.284 | 1988 | 10.128 | 1987 | 11.257 | 1986 | 11.28 | 1985 | 11.321 | 1984 | 11.882 | 1983 | 11.66 | 1982 | 13 | 1981 | 11.35 | 1980 | 9.1 | 1979 | 6.96 | 1978 | 7.9 | 1977 | 5.67 | 1976 | 6.5 | 1975 | 5.1 | 1974 | 3 | 1973 | 2.8 | 1972 | 2.7 | 1971 | 2.1 |
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