Year % of total population 1960 28.092478334493567 1961 28.14541674102817 1962 28.017264703700288 1963 27.82743650179019 1964 27.671192359663877 1965 27.564053282583664 1966 27.38402954568754 1967 27.159367970972035 1968 26.97241136515476 1969 26.75962997323602 1970 26.523618811979365 1971 26.267715395462755 1972 25.987950920855248 1973 25.667764532771514 1974 25.31781333154745 1975 24.93539340029409 1976 24.51867616536183 1977 24.091369278301865 1978 23.655554430201143 1979 23.227278972224052 1980 22.834299607687704 1981 22.497554072631253 1982 22.184800755588213 1983 21.86416682035142 1984 21.54512678026216 1985 21.221608557995307 1986 20.898392222312843 1987 20.604037894025964 1988 20.356744147540436 1989 20.139229858607024 1990 19.952808461132808 1991 19.786804652240917 1992 19.64117527871743 1993 19.506674095550963 1994 19.34330073761374 1995 19.150405995098133 1996 18.953569319668002 1997 18.770902706502994 1998 18.594728080342975 1999 18.422507957190696 2000 18.248746856210687 2001 18.06166736483654 2002 17.870793832795574 2003 17.682675905969447 2004 17.490293094099894 2005 17.29580936641926 2006 17.117767800610437 2007 16.969585457074515 2008 16.855355850041374 2009 16.761199382784845 2010 16.672216075789912 2011 16.59366276367085 2012 16.52011460894894 2013 16.450814888730683 2014 16.37955648760268 2015 16.302924403264306 2016 16.231656647858966 2017 16.165153613584135 2018 16.076146475422224 2019 15.96147214708977 2020 15.829265753978989 2021 15.6709878981251 2022 15.503794488773668 2023 15.309008032057468