Year % of total population 1960 28.087297387923996 1961 28.290149629901293 1962 28.302843655990667 1963 28.246002471156196 1964 28.125249471777742 1965 27.95817988413011 1966 27.789725381691298 1967 27.622598006170502 1968 27.43633702368586 1969 27.21255349223593 1970 26.946532323458097 1971 26.675584978127013 1972 26.407336390273052 1973 26.123108289925916 1974 25.829502771516857 1975 25.526490007480003 1976 25.220460873815135 1977 24.91981610484231 1978 24.613776620607446 1979 24.333611988539126 1980 24.10976813661085 1981 23.922032585908735 1982 23.753975035073122 1983 23.598209996329842 1984 23.460507261445827 1985 23.33929147169382 1986 23.21566603390705 1987 23.09043876004636 1988 22.972437493299832 1989 22.836336912892254 1990 22.67771651877686 1991 22.48991656636427 1992 22.290221639618192 1993 22.08842662112272 1994 21.85516933947903 1995 21.58792063346851 1996 21.29870926953334 1997 20.984674004667344 1998 20.632099082407365 1999 20.25676456181501 2000 19.877514955515515 2001 19.479890188949696 2002 19.07126834658398 2003 18.701336267867216 2004 18.384284841702968 2005 18.101070673999207 2006 17.864548907481584 2007 17.69139179617396 2008 17.60148156312985 2009 17.568415109184564 2010 17.556445712796663 2011 17.566093948609687 2012 17.593200333773886 2013 17.637974583176927 2014 17.69553250042366 2015 17.7649507710369 2016 17.839325125882503 2017 17.9100632965256 2018 17.9562769744738 2019 17.970788180414885 2020 17.95858837858523 2021 17.936248282720396 2022 17.887603572423387 2023 17.75369384898442