Year % of total population 1960 28.6964654008943 1961 29.2802295819437 1962 29.6823180123733 1963 29.9140228163429 1964 30.0181113464476 1965 29.9945095632274 1966 30.1347153395996 1967 30.4923825136612 1968 30.7607236645433 1969 30.8622363641887 1970 30.6337676454373 1971 30.169623444326 1972 29.6819726679477 1973 29.1737223520544 1974 28.6334905791762 1975 28.0734339036521 1976 27.5312464224227 1977 27.0142727288237 1978 26.5270948161733 1979 26.1067964716794 1980 25.8064202690968 1981 25.6219107573236 1982 25.5023361744216 1983 25.3988420259972 1984 25.3058307160109 1985 25.2327225982591 1986 25.1603667906856 1987 25.0912516168061 1988 25.0070892693828 1989 24.932882427385 1990 24.955915510238 1991 25.0357306896678 1992 25.0791346790213 1993 25.0795463920019 1994 25.0260258631953 1995 24.9045652068731 1996 24.7261236073049 1997 24.4945185722857 1998 24.1921983531799 1999 23.7995876892038 2000 23.320806288703 2001 22.7701342134113 2002 22.1641526891239 2003 21.5440096997766 2004 20.9263449865808 2005 20.2870658665855 2006 19.6696253750285 2007 19.1832115460746 2008 18.8812867804032 2009 18.7571097163714 2010 18.71523661063 2011 18.6946019820696 2012 18.7109986552257 2013 18.7752846159789 2014 19.0039173501385 2015 19.3810240532551 2016 19.7683175510659 2017 20.1268856544447 2018 20.4501865560364 2019 20.7125497290304 2020 20.9070472172478 2021 21.0943113055418 2022 21.2641566954044 2023 21.3242050896365