Year % of total population 1960 25.631403566014 1961 25.1297097667236 1962 24.474982878871 1963 23.9222650529399 1964 23.5381631893534 1965 23.1742097327247 1966 22.7472304853637 1967 22.3069453360778 1968 21.9090319304355 1969 21.5826532114293 1970 21.331513971782 1971 21.1601246018331 1972 21.1069470141202 1973 21.2527378613044 1974 21.6388931360666 1975 22.12448798537 1976 22.5716540009315 1977 22.9533415105073 1978 23.2289657632504 1979 23.3814023908421 1980 23.4580945263175 1981 23.4990583036845 1982 23.5183970219427 1983 23.5223725316474 1984 23.4894326439825 1985 23.3979842706387 1986 23.2356192757613 1987 22.9739192524385 1988 22.5730705447668 1989 22.0304041085757 1990 21.4242380190449 1991 20.8584741979596 1992 20.3173362546274 1993 19.7750413039974 1994 19.2172983981431 1995 18.673779556469 1996 18.1854066343158 1997 17.726219591714 1998 17.2963120744615 1999 16.879980353487 2000 16.4653321882105 2001 16.0653730163292 2002 15.695759105387 2003 15.3396735716473 2004 15.0075250957533 2005 14.7099793552853 2006 14.4461448361761 2007 14.2767548196048 2008 14.2087701182329 2009 14.2417413599373 2010 14.4022231206883 2011 14.5912516397918 2012 14.7541526360151 2013 14.9214957079724 2014 15.0978330078263 2015 15.2715785342696 2016 15.4296845037808 2017 15.57872457402 2018 15.7260607979824 2019 15.8637464575584 2020 15.9618120049623 2021 16.0029438430681 2022 15.9524750652421 2023 15.7917190512511