Year % of total population 1960 37.543934391309 1961 35.639179381679 1962 35.8960361104084 1963 36.0547428032091 1964 36.2190751243954 1965 36.4961216861483 1966 36.7072434607646 1967 36.7120040634347 1968 36.5263855155664 1969 36.1464052723228 1970 36.3201487891182 1971 37.0889395497147 1972 37.7074385177976 1973 38.0464897863348 1974 38.1307740144507 1975 38.1849241414061 1976 38.2549107564454 1977 38.1316345782284 1978 37.6459875036343 1979 36.8031495227433 1980 35.872826986755 1981 34.9976057299467 1982 34.1946810062526 1983 33.5287711289144 1984 32.9066632493629 1985 32.2202870109162 1986 31.5426429608697 1987 30.9825462921946 1988 30.5921621955742 1989 30.3771899349844 1990 30.2711426726921 1991 30.2612226706613 1992 30.3387994287684 1993 30.4335056390977 1994 30.4317962607535 1995 29.9646701174924 1996 29.2064493314601 1997 28.5059318428889 1998 27.7687064008571 1999 26.9955576989066 2000 26.3585524795489 2001 25.8115289891302 2002 25.1853089565609 2003 24.5157892774588 2004 23.8348182082197 2005 23.1585916736319 2006 22.5105502067794 2007 21.9362198551262 2008 21.4416521102158 2009 21.0393830952314 2010 20.6765465131616 2011 20.3134258315597 2012 19.9946551115268 2013 19.7481212400776 2014 19.5839741543581 2015 19.4842588044181 2016 19.4227658565906 2017 19.3846893992204 2018 19.3455302398769 2019 19.2801495638547 2020 19.2642556686662 2021 19.2429888801191 2022 19.1796109184135 2023 19.0992405063291