Year | Value | 2022 | 6 | 2021 | 7.9 | 2019 | 8.3 | 2018 | 9.2 | 2017 | 10.8 | 2016 | 11.8 | 2015 | 12 | 2014 | 13.9 | 2013 | 14.3 | 2012 | 14.5 | 2011 | 15.7 | 2010 | 16.1 | 2009 | 15 | 2008 | 11.48 | 2007 | 10.93 | 2006 | 11.01 | 2005 | 11.35 | 2004 | 10.31 | 2003 | 11.78 | 2002 | 11.94 | 2001 | 11.4 | 2000 | 10.08 | 1999 | 11.81 | 1998 | 13.46 | 1997 | 13.8 | 1996 | 13.64 | 1995 | 13.93 | 1994 | 14.6 | 1993 | 16.91 | 1992 | 16.93 | 1991 | 16.18 | 1990 | 14.52 | 1989 | 14.6 | 1988 | 15.01 | 1987 | 17.01 | 1986 | 19.53 | 1985 | 20.67 | 1984 | 20 | 1983 | 22.24 | 1982 | 19.91 | 1981 | 17.83 | 1980 | 17.1 | 1979 | 14.53 | 1978 | 16.73 | 1977 | 19.04 | 1976 | 19.65 | 1974 | 13.13 | 1973 | 11.61 | 1972 | 11.83 | 1971 | 11.52 |
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