Year % of total population 1960 55.956 1961 55.266 1962 54.339 1963 53.263 1964 52.182 1965 51.102 1966 50.02 1967 48.938 1968 47.855 1969 46.778 1970 45.702 1971 44.629 1972 43.561 1973 42.501 1974 41.447 1975 40.4 1976 39.836 1977 39.277 1978 38.719 1979 38.164 1980 37.612 1981 37.064 1982 36.519 1983 35.977999999999994 1984 35.43899999999999 1985 34.905 1986 34.373999999999995 1987 33.848 1988 33.324 1989 32.806 1990 32.291 1991 31.781000000000006 1992 31.274 1993 30.772999999999996 1994 30.275999999999996 1995 29.784000000000006 1996 29.295 1997 28.813000000000002 1998 28.476 1999 28.253 2000 28.031000000000006 2001 27.811000000000007 2002 27.590999999999994 2003 27.373000000000005 2004 27.155 2005 26.938999999999993 2006 26.724000000000004 2007 26.509 2008 26.296000000000006 2009 26.076999999999998 2010 25.851 2011 25.619 2012 25.381 2013 25.137 2014 24.887 2015 24.632000000000005 2016 24.372 2017 24.105999999999995 2018 23.836 2019 23.560000000000002 2020 23.281000000000006 2021 22.997 2022 22.709000000000003 2023 22.418000000000006