Year % of total population 1960 23.6733061443791 1961 23.7938689654729 1962 23.8117826671301 1963 23.8476224969441 1964 23.9040413703401 1965 23.9562211889764 1966 23.9819397926182 1967 23.9546140216586 1968 23.8687983806207 1969 23.7497993140188 1970 23.6112184216298 1971 23.4593299777218 1972 23.260914252325 1973 22.9856609491385 1974 22.6324125766118 1975 22.2415699319588 1976 21.8390895742248 1977 21.4323671582737 1978 21.0266050033339 1979 20.6093577361595 1980 20.222804276189 1981 19.8956549547998 1982 19.6112238161553 1983 19.3554584326083 1984 19.1020458141937 1985 18.8347553464845 1986 18.5797620606777 1987 18.3631144010263 1988 18.2072939137396 1989 18.1254522162749 1990 18.1089767967171 1991 18.1259017910158 1992 18.1370055573554 1993 18.1204638093674 1994 18.0586119110768 1995 17.9633128542897 1996 17.8643238306511 1997 17.7785590119423 1998 17.7086897898742 1999 17.6501670714164 2000 17.6079714799073 2001 17.5568546147683 2002 17.4749169975555 2003 17.3742679739935 2004 17.2677739084487 2005 17.1603667897755 2006 17.0512970124185 2007 16.9549601868234 2008 16.9027827342497 2009 16.9009373961502 2010 16.9283145490741 2011 16.9536067500674 2012 16.966479301617 2013 16.9806391043637 2014 16.9897607733501 2015 16.9822053610129 2016 16.964291079238 2017 16.9495347156322 2018 16.928264257393 2019 16.8743106334978 2020 16.7934968825779 2021 16.6881103554996 2022 16.5336142204011 2023 16.3401473882736