Year % of total population 1960 37.461862677633 1961 38.3788577222708 1962 38.7802786388838 1963 38.9427463950298 1964 38.9074967841601 1965 38.7275010418537 1966 38.4566184371464 1967 38.1122773872504 1968 37.6898590604218 1969 37.2156518457269 1970 36.7665474591356 1971 36.339217080089 1972 35.8588413872918 1973 35.2951287783031 1974 34.6800644979889 1975 34.0459767188739 1976 33.4220491522176 1977 32.8487892051406 1978 32.3414525430243 1979 31.9357857025411 1980 31.6399957509892 1981 31.451851241659 1982 31.3773495595482 1983 31.4043106104098 1984 31.5125320764733 1985 31.6439497812103 1986 31.7340592025902 1987 31.7671808842165 1988 31.7497697891555 1989 31.7432737548371 1990 31.7234756126663 1991 31.6226360779277 1992 31.4865323074592 1993 31.3248375397983 1994 31.1612554278635 1995 30.975685400872 1996 30.5524243232768 1997 29.8922409290796 1998 29.16105909981 1999 28.5341389482543 2000 27.9547086791847 2001 27.2376504986328 2002 26.4762096368575 2003 25.7468486146722 2004 25.1267006390478 2005 24.6493788087229 2006 24.3282709172895 2007 24.18815272431 2008 24.2233530826412 2009 24.3798601403206 2010 24.623489051026 2011 24.9722004273072 2012 25.4210106149178 2013 25.9171226073688 2014 26.4495129189351 2015 27.0021989628395 2016 27.5497913895485 2017 28.0564192461905 2018 28.5021673473639 2019 28.8901539053158 2020 29.2444540596271 2021 29.5326058851824 2022 29.6657521049337 2023 29.634720310348