Year | Value | 2023 | 11.494 | 2022 | 11.612 | 2021 | 12.881 | 2020 | 13.053 | 2019 | 13.588 | 2018 | 14.334 | 2017 | 14.905 | 2016 | 15.818 | 2015 | 16.021 | 2014 | 16.09 | 2013 | 15.065 | 2012 | 14.856 | 2011 | 14.987 | 2010 | 15.638 | 2009 | 15.939 | 2008 | 14.697 | 2007 | 13.591 | 2006 | 12.906 | 2005 | 12.563 | 2004 | 12.326 | 2003 | 12.132 | 2002 | 12.206 | 2001 | 12.248 | 2000 | 12.452 | 1999 | 12.682 | 1998 | 13.14 | 1997 | 13.367 | 1996 | 13.654 | 1995 | 14.076 | 1994 | 14.368 | 1993 | 15.062 | 1992 | 16.179 | 1991 | 17.686 | 1990 | 18.77 | 1989 | 18.962 | 1988 | 19.152 | 1987 | 19.475 | 1986 | 20.266 | 1985 | 20.598 | 1984 | 20.45 | 1983 | 20.077 | 1982 | 19.737 | 1981 | 19.666 | 1980 | 19.506 | 1979 | 19.324 | 1978 | 19.158 | 1977 | 18.917 | 1976 | 19.051 | 1975 | 19.076 |
|