Year % of total population 1960 31.4634568296669 1961 31.4791818645153 1962 31.3209824060024 1963 31.040019150693 1964 30.7630229765038 1965 30.3941103398032 1966 29.8761178791926 1967 29.2734678173159 1968 28.6483609980071 1969 28.0645378152757 1970 27.5475268231412 1971 27.0449988782233 1972 26.5787095502021 1973 26.2543846920129 1974 26.1112547850073 1975 26.0551219649154 1976 26.0176846934794 1977 26.044527589616 1978 26.0843055534936 1979 26.0974950656235 1980 26.1037000669296 1981 26.1299444751225 1982 26.2139459147865 1983 26.3415686551126 1984 26.4379796760182 1985 26.4772602962244 1986 26.4583720983705 1987 26.3280367086354 1988 26.0776744777133 1989 25.7128032474385 1990 25.268597809859 1991 24.826008884278 1992 24.3715050804972 1993 23.8779791161341 1994 23.3195649742986 1995 22.7169774783965 1996 22.1261021941892 1997 21.5337648665285 1998 20.9360016108491 1999 20.3285422663796 2000 19.7003937088054 2001 19.054040343122 2002 18.433619102226 2003 17.8577306330754 2004 17.3390055927235 2005 16.8750975937372 2006 16.4324493506003 2007 16.0387175920193 2008 15.7185859205812 2009 15.5220339338456 2010 15.4469515367955 2011 15.4128243217093 2012 15.3723871192922 2013 15.3326503825946 2014 15.3154153033202 2015 15.3216241773697 2016 15.3959154725099 2017 15.535811607734 2018 15.6791427100826 2019 15.787532059486 2020 15.8419573951599 2021 15.8810670050161 2022 15.7396012689394 2023 15.6286263853925