Year | Value | 2022 | 6.805 | 2021 | 8.736 | 2020 | 11.461 | 2019 | 9.843 | 2018 | 9.221 | 2017 | 8.347 | 2014 | 7.268 | 2013 | 7.1 | 2012 | 7.217 | 2011 | 7.18 | 2010 | 7.714 | 2009 | 8.645 | 2008 | 7.837 | 2007 | 8.47 | 2006 | 10.078 | 2005 | 11.506 | 2004 | 13.522 | 2003 | 15.36 | 2002 | 19.59 | 2001 | 17.32 | 2000 | 15 | 1999 | 14.05 | 1998 | 12.65 | 1997 | 14.82 | 1996 | 17.11 | 1995 | 18.8 | 1994 | 11.76 | 1993 | 10.1 | 1992 | 6.36 | 1991 | 6.32 | 1990 | 7.06 | 1989 | 7.3 | 1988 | 6 | 1987 | 5.3 | 1986 | 4.4 | 1985 | 5.3 | 1984 | 3.54 | 1983 | 4.17 | 1982 | 4.73 | 1981 | 4.5 | 1980 | 2.3 | 1979 | 2 | 1978 | 2.8 | 1977 | 2.8 | 1976 | 4.5 | 1975 | 2.3 | 1974 | 3.4 | 1973 | 5.6 | 1972 | 6.6 | 1971 | 6 | 1970 | 4.8 |
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