Year % of total population 1960 20.154663345320706 1961 21.388378608494975 1962 22.581875668953806 1963 23.766660151523613 1964 25.024372769267995 1965 26.34100005997187 1966 26.88650288997406 1967 27.101491303273704 1968 27.31501686520028 1969 27.524093999865144 1970 27.732175816429688 1971 27.95321640882141 1972 28.189846787690293 1973 28.428048979138325 1974 28.6898880437913 1975 28.980388585547022 1976 29.291606156404242 1977 29.59018369879816 1978 29.560979825825974 1979 29.44041898679369 1980 29.33994532777954 1981 29.278345605327548 1982 29.271911008273477 1983 29.219268965897616 1984 29.12350055589401 1985 29.232620889768196 1986 29.3295713503054 1987 29.347454054607358 1988 29.494030438892572 1989 29.54530835156935 1990 30.022729716840974 1991 30.563182064170107 1992 30.526763964528246 1993 29.93107625704181 1994 29.3557416550207 1995 29.205000100721477 1996 29.10601861462267 1997 29.03682228602059 1998 28.890938325688502 1999 28.692671686775057 2000 28.479286372108685 2001 28.308791790404836 2002 28.132974686333366 2003 28.00344883854019 2004 26.821637342515594 2005 25.68245638022984 2006 25.167051499731524 2007 25.068596097531803 2008 25.534405893331325 2009 25.58634740486988 2010 25.39422914692606 2011 25.121482722513868 2012 24.60805871124959 2013 24.061270848716806 2014 23.803028469006343 2015 23.73403618477585 2016 23.726961404641067 2017 23.74279431784459 2018 23.744781440083564 2019 23.764062812774277 2020 23.79492400119332 2021 23.86166296592296 2022 23.96313773141848 2023 24.066706721260463