Year % of total population 1960 12.20958019209719 1961 12.38287484108307 1962 12.537089040404336 1963 12.684808604189476 1964 12.870633895485872 1965 13.833178830073079 1966 15.020309443848282 1967 16.3271444940846 1968 17.738498499224743 1969 19.248849729684466 1970 20.8701969487376 1971 22.60927733976061 1972 24.447236580358865 1973 26.230846882532667 1974 25.924661588311892 1975 25.313317983228327 1976 24.679131313800877 1977 24.062506761927054 1978 23.466724362200907 1979 22.89066380017587 1980 22.347673759248256 1981 21.844399850257794 1982 21.375323576454996 1983 20.933861277862547 1984 20.645119842717744 1985 20.50802958380572 1986 20.41546165768886 1987 20.362817518371322 1988 20.338798452841118 1989 20.334103139871218 1990 20.35153315460553 1991 20.391154155566678 1992 20.45338168924726 1993 20.53747329465321 1994 20.64968491559254 1995 20.791462103927202 1996 20.61473847038609 1997 20.409881309887144 1998 20.227799368876937 1999 20.058608168686504 2000 19.81939128461101 2001 19.499211132246987 2002 19.165079035011022 2003 18.8205947309234 2004 18.46910530925108 2005 18.118508677478843 2006 17.831327681246545 2007 17.591042543131024 2008 17.340588308016383 2009 17.09958081447554 2010 16.869239437904074 2011 17.82096761995381 2012 18.918187285238 2013 18.682952559312348 2014 18.465998356118735 2015 18.31104601165815 2016 18.174679682072956 2017 18.02575968590812 2018 17.87253776093185 2019 17.672437939634847 2020 17.509695756290032 2021 17.368105276145286 2022 17.26029275398868 2023 17.178068366648336