Year % of total population 1960 31.078715813398436 1961 31.181558122096007 1962 31.03480595124818 1963 30.87196153156668 1964 30.823716601550498 1965 30.8302432816698 1966 30.491740383661735 1967 29.953760598460047 1968 29.497160473700742 1969 28.98672347886945 1970 28.45859258919078 1971 27.89800996569959 1972 27.265613297803558 1973 26.577834527844036 1974 25.895835771118016 1975 25.215260599663257 1976 24.53637361507957 1977 23.915588354641688 1978 23.35950982545031 1979 22.876286248620904 1980 22.50149210949933 1981 22.237221674768723 1982 22.04769102640097 1983 21.873023770217983 1984 21.694517122053643 1985 21.50833644754841 1986 21.344315598533264 1987 21.2781901427994 1988 21.305365804930265 1989 21.373708271278016 1990 21.471633042028635 1991 21.5849947681543 1992 21.68240813500202 1993 21.738562361990294 1994 21.730331106341048 1995 21.662688841547386 1996 21.57043000853737 1997 21.484671057157417 1998 21.408144841594396 1999 21.32383422353203 2000 21.20474752242785 2001 21.048761454726794 2002 20.889154286833364 2003 20.728422720406336 2004 20.539391565151508 2005 20.322941262856556 2006 20.119690734137894 2007 19.955233338194308 2008 19.817569881933462 2009 19.68229248649776 2010 19.53846078282409 2011 19.41301617118206 2012 19.311288335352316 2013 19.210044092488808 2014 19.104184525678 2015 18.989859352984364 2016 18.877054665732125 2017 18.76411442893941 2018 18.62267213808613 2019 18.452414026765034 2020 18.238804224565932 2021 17.983329283156397 2022 17.70969444373943 2023 17.431635886425575