Year | Value | 2019 | 7 | 2018 | 7.2 | 2016 | 8.8 | 2012 | 9.5 | 2010 | 9.8 | 2009 | 9.9 | 2008 | 10.4 | 2007 | 10.1 | 2006 | 10.6 | 2005 | 10.7 | 2004 | 10.9 | 2003 | 10.3 | 2002 | 11.2 | 2001 | 11.8 | 2000 | 11.3 | 1999 | 12.6 | 1998 | 11.9 | 1997 | 11.2 | 1996 | 10.9 | 1995 | 11 | 1994 | 10.9 | 1993 | 11.4 | 1992 | 12.1 | 1991 | 11.9 | 1990 | 11.9 | 1989 | 12.5 | 1988 | 11.6 | 1987 | 11 | 1986 | 11.9 |
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