Year | Value | 2021 | 17.243856737747 | 2020 | 17.243856737747 | 2019 | 17.243856737747 | 2018 | 17.243856737747 | 2017 | 17.243856737747 | 2016 | 17.184189640358 | 2015 | 17.124511610924 | 2014 | 17.064844513535 | 2013 | 17.005166484102 | 2012 | 16.945488454668 | 2011 | 17.093562993718 | 2010 | 17.241637532769 | 2009 | 17.389712071819 | 2008 | 17.537786610869 | 2007 | 17.6578708393 | 2006 | 17.902939558521 | 2005 | 18.148008277741 | 2004 | 18.393076996961 | 2003 | 18.634882208096 | 2002 | 18.879994586288 | 2001 | 19.144458803395 | 2000 | 19.140966085711 | 1999 | 19.147152078402 | 1998 | 19.301536418982 | 1997 | 19.389974407575 | 1996 | 19.544358748155 | 1995 | 19.853673342825 | 1994 | 19.864591613022 | 1993 | 19.952920418912 | 1992 | 20.098351777931 | 1991 | 20.272607370269 | 1990 | 20.272607370269 | 1989 | 20.278066505367 | 1988 | 20.279813428599 | 1987 | 20.279813428599 | 1986 | 20.500690034676 | 1985 | 20.500690034676 | 1984 | 20.500690034676 | 1983 | 20.500690034676 | 1982 | 20.500690034676 | 1981 | 20.608780909623 | 1980 | 20.608780909623 | 1979 | 20.608780909623 | 1978 | 20.608780909623 | 1977 | 20.368251417192 | 1976 | 20.359516801034 | 1975 | 20.359516801034 | 1974 | 20.359516801034 | 1973 | 20.422624402771 | 1972 | 20.476669840244 | 1971 | 20.541633547914 | 1970 | 20.606597255584 | 1969 | 20.662171250884 | 1968 | 19.762069055875 | 1967 | 19.05096211797 | 1966 | 19.183946648965 | 1965 | 19.325338248011 | 1964 | 19.43080873811 | 1963 | 19.606374522872 | 1962 | 19.335710604697 | 1961 | 19.721671456148 |
|