Year | Value | 2021 | 7.7 | 2020 | 8.4 | 2019 | 8.2 | 2018 | 8.3 | 2017 | 9 | 2016 | 9.3 | 2015 | 9.4 | 2014 | 9.3 | 2013 | 10.5 | 2012 | 10.4 | 2011 | 10.6 | 2010 | 12 | 2009 | 12.5 | 2008 | 12.8 | 2007 | 13.4 | 2006 | 12.5 | 2005 | 13.1 | 2004 | 13.2 | 2003 | 13.2 | 2002 | 13.2 | 2001 | 13.3 | 2000 | 13.5 | 1996 | 13.9 | 1995 | 13.3 | 1994 | 14.5 | 1993 | 13.7 | 1992 | 15.5 | 1991 | 15.4 | 1990 | 14.6 | 1989 | 15.2 | 1984 | 15.1 | 1980 | 14.9 | 1979 | 14.5 | 1978 | 13 | 1977 | 14.3 | 1976 | 15.2 | 1970 | 20.3 | 1966 | 20.3 | 1962 | 26 | 1960 | 28.3 |
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