Year % of total population 1960 37.5716242278559 1961 37.8193223733194 1962 38.1660697784345 1963 38.4016144109922 1964 38.5727978246367 1965 38.6163273291024 1966 38.4810519342206 1967 38.2257417299927 1968 37.8536042466898 1969 37.3510976998595 1970 36.7152450113299 1971 35.9652072729673 1972 35.1261819287105 1973 34.2283127420624 1974 33.2864214503907 1975 32.3041557647906 1976 31.3054262067688 1977 30.3441038519925 1978 29.4746403515412 1979 28.7149175299405 1980 28.0361392805665 1981 27.4379769400059 1982 26.9482322935981 1983 26.5572338886842 1984 26.237132135021 1985 25.9486799709977 1986 25.6434570577079 1987 25.2975016817834 1988 24.9161872998881 1989 24.5359581695709 1990 24.1642458704823 1991 23.8003176536804 1992 23.4919536916943 1993 23.2436957725325 1994 23.0284110556854 1995 22.8435762389751 1996 22.6736962672212 1997 22.4806201550388 1998 22.2599628662407 1999 22.0693531993663 2000 21.8822853731434 2001 21.6588507271744 2002 21.4580323131486 2003 21.285873965884 2004 21.0837787005829 2005 20.8271948997503 2006 20.5490976257786 2007 20.3205817774569 2008 20.2193037957273 2009 20.1874419037845 2010 20.0882017829646 2011 19.908598061974 2012 19.686094189846 2013 19.4275188268651 2014 19.1341763576018 2015 18.8035586497556 2016 18.4608593607011 2017 18.1437531117137 2018 17.8623718887262 2019 17.6049639606038 2020 17.3732512032719 2021 17.162192678152 2022 16.9249205531983 2023 16.6231376032596