Year | Value | 2019 | 8.413 | 2018 | 8.322 | 2017 | 8.622 | 2016 | 8.247 | 2015 | 9.803 | 2014 | 12.17 | 2013 | 11.55 | 2010 | 10.69 | 2009 | 10.02 | 2003 | 11 | 2002 | 10.32 | 2001 | 9.85 | 2000 | 9.35 | 1999 | 10.61 | 1998 | 12.4 | 1997 | 14.61 | 1996 | 14.71 | 1995 | 19.66 | 1994 | 22.98 | 1993 | 24.54 | 1992 | 22.94 | 1991 | 7.52 | 1990 | 8.16 | 1989 | 14.06 | 1988 | 17.57 | 1987 | 17.94 | 1986 | 17.88 | 1985 | 18.85 | 1984 | 17.02 | 1983 | 9.06 | 1982 | 8.39 | 1981 | 7.23 | 1980 | 8.98 | 1979 | 9.45 | 1978 | 13.29 | 1977 | 12.45 | 1976 | 9.86 |
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