Year | Value | 2022 | 4.383 | 2021 | 4.446 | 2020 | 4.206 | 2019 | 3.523 | 2016 | 3.207 | 2015 | 2.428 | 2014 | 2.477 | 2013 | 2.683 | 2012 | 3.718 | 2011 | 3.425 | 2010 | 4.033 | 2009 | 5.28 | 2008 | 4.63 | 2007 | 5.54 | 2006 | 6.27 | 2005 | 7.95 | 2004 | 8.33 | 2003 | 10.48 | 2002 | 10.39 | 2001 | 10.88 | 2000 | 12.1 | 1999 | 13.12 | 1998 | 14.21 | 1997 | 15.01 | 1996 | 16.25 | 1995 | 17.22 | 1994 | 18.44 | 1993 | 19.81 | 1992 | 19.66 | 1991 | 18.52 | 1990 | 21.86 | 1989 | 21.95 | 1988 | 21.88 | 1987 | 22.11 | 1986 | 9.37 | 1985 | 9.31 | 1984 | 8.17 | 1983 | 6.61 | 1982 | 6.22 | 1981 | 6.31 | 1980 | 6.03 | 1979 | 6.75 | 1978 | 7.27 | 1977 | 8.98 | 1975 | 14.99 | 1974 | 15.24 | 1973 | 15.4 | 1971 | 13.03 | 1970 | 12.76 | 1969 | 13.17 |
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