Year | Value | 2021 | 27.21465807889 | 2020 | 26.734382076706 | 2019 | 27.412701829584 | 2018 | 27.909146603384 | 2017 | 28.12738508666 | 2016 | 28.120504703138 | 2015 | 27.136841709952 | 2014 | 26.514890814054 | 2013 | 26.467540628006 | 2012 | 26.303910730344 | 2011 | 26.632733398517 | 2010 | 27.399518857975 | 2009 | 27.233538461262 | 2008 | 27.471937162924 | 2007 | 28.50704067551 | 2006 | 28.560308142954 | 2005 | 28.556865461084 | 2004 | 27.253502763415 | 2003 | 26.894480629365 | 2002 | 26.763166888347 | 2001 | 27.892812766228 | 2000 | 29.85892495944 | 1999 | 30.297850204063 | 1998 | 29.670561404242 | 1997 | 27.514850271264 | 1996 | 27.311220312058 | 1995 | 26.732390274039 | 1994 | 14.821559022263 | 1993 | 15.446747845099 | 1992 | 17.141863462107 | 1991 | 19.66714805131 | 1990 | 21.619996235216 | 1989 | 21.287589263009 | 1988 | 21.672404531568 | 1987 | 21.570135744512 | 1986 | 19.146749790393 | 1985 | 20.193348048603 | 1984 | 17.690849680672 | 1983 | 16.83525574152 | 1982 | 16.370554725737 | 1981 | 16.711925135607 | 1980 | 16.303029029581 | 1979 | 16.804359478472 | 1978 | 18.312318581013 | 1977 | 19.970658885937 | 1976 | 19.365334532378 | 1975 | 16.480862377279 | 1974 | 17.071611746493 | 1973 | 17.587928299732 | 1972 | 19.031546574934 |
|