Year | Value | 2022 | 9.231 | 2021 | 13.159 | 2020 | 13.697 | 2019 | 11.936 | 2018 | 12.33 | 2017 | 12.792 | 2016 | 11.58 | 2015 | 8.538 | 2014 | 6.755 | 2013 | 7.071 | 2012 | 7.251 | 2011 | 7.578 | 2009 | 9.419 | 2008 | 8.268 | 2007 | 9.28 | 2006 | 9.692 | 2005 | 10.551 | 2004 | 10.072 | 2003 | 11.169 | 2002 | 10.641 | 2001 | 10.649 | 1999 | 11.125 | 1998 | 10.15 | 1997 | 9.003 | 1996 | 8.035 | 1995 | 7.092 | 1993 | 6.03 | 1992 | 7.086 | 1990 | 4.703 | 1989 | 4.145 | 1988 | 3.79 | 1987 | 3.56 | 1986 | 2.37 | 1985 | 3.38 | 1984 | 4.04 | 1983 | 4.62 | 1982 | 4.83 | 1981 | 3.99 | 1979 | 2.76 | 1978 | 2.36 | 1977 | 2.32 | 1976 | 1.92 | 1973 | 2.78 | 1972 | 3.06 |
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