Year | Value | 2022 | 6.807 | 2021 | 7.513 | 2020 | 7.755 | 2019 | 7.155 | 2018 | 8.504 | 2017 | 11.155 | 2016 | 13.006 | 2015 | 15.026 | 2014 | 16.277 | 2013 | 16.131 | 2012 | 12.097 | 2011 | 10.99 | 2010 | 6.36 | 2009 | 5.594 | 2008 | 3.756 | 2007 | 3.946 | 2006 | 4.593 | 2005 | 5.481 | 2004 | 4.77 | 2003 | 4.153 | 2002 | 3.336 | 2001 | 3.45 | 2000 | 4.766 | 1999 | 5.532 | 1998 | 3.3 | 1997 | 3.4 | 1996 | 3.1 | 1995 | 2.6 | 1994 | 2.7 | 1993 | 2.7 | 1992 | 2.09 | 1991 | 3 | 1990 | 1.8 | 1989 | 2.3 | 1988 | 2.8 | 1987 | 3.4 | 1986 | 3.7 | 1985 | 3.3 | 1984 | 3.3 | 1983 | 3.3 | 1982 | 2.8 | 1981 | 2.6 | 1980 | 2 | 1979 | 1.7 | 1978 | 2 | 1977 | 3.1 | 1976 | 7.4 | 1975 | 10.9 |
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