Year % of total population 1960 19.688556067588326 1961 19.81912193541419 1962 19.96295508337101 1963 20.117135295196668 1964 20.2858693124564 1965 20.473888208894326 1966 20.70012857034815 1967 20.962928753307704 1968 21.245404843777056 1969 21.524177143837463 1970 21.77829558969878 1971 21.992049003122748 1972 22.215133284189 1973 22.468497348261636 1974 22.728169178642364 1975 23.02082946743366 1976 23.321849668386147 1977 23.634820795498733 1978 23.9761011437797 1979 24.23211141709178 1980 24.40179510710209 1981 24.577178377178377 1982 24.74784274016025 1983 24.911649828711077 1984 25.0833585738393 1985 25.24941559973407 1986 25.41417791476246 1987 25.596036681775058 1988 25.73734527313336 1989 25.752690858368204 1990 25.48590170762182 1991 25.038276225728406 1992 24.580691494818918 1993 24.133615686913316 1994 24.24755111375421 1995 24.90848530676584 1996 25.55427244790891 1997 26.107165821477352 1998 26.47674490121258 1999 26.739900394304616 2000 26.974801643606742 2001 27.105752255707184 2002 27.18504266038962 2003 27.362581913366686 2004 27.5258062709111 2005 27.6944416470701 2006 27.845525155353375 2007 27.984294943367605 2008 28.062577937241727 2009 28.306014625032017 2010 28.50625677536744 2011 28.72881538669182 2012 28.934123276892702 2013 29.014236881830225 2014 28.993518871521157 2015 28.940808681021217 2016 28.916419964560745 2017 28.90546791258808 2018 28.909669509243002 2019 28.959660616838896 2020 28.95286667046318 2021 29.090306071547023 2022 29.100294087383656 2023 28.780317868079297