Year % of total population 1960 43.433 1961 42.697 1962 41.692 1963 40.694 1964 39.702 1965 38.722 1966 37.749 1967 36.786 1968 35.831999999999994 1969 34.891999999999996 1970 33.962 1971 33.152 1972 32.459 1973 31.775999999999996 1974 31.099000000000004 1975 30.430000000000007 1976 29.769000000000005 1977 29.117000000000004 1978 28.473 1979 27.837999999999994 1980 27.211 1981 26.721000000000004 1982 26.485 1983 26.251000000000005 1984 26.018 1985 25.787000000000006 1986 25.555999999999997 1987 25.326999999999998 1988 25.099999999999994 1989 24.873999999999995 1990 24.649 1991 24.471999999999994 1992 24.39 1993 24.308000000000007 1994 24.226 1995 24.144000000000005 1996 24.061999999999998 1997 23.980999999999995 1998 23.900000000000006 1999 23.819000000000003 2000 23.738 2001 23.656999999999996 2002 23.467 2003 23.221999999999994 2004 22.977999999999994 2005 22.736999999999995 2006 22.498000000000005 2007 22.260000000000005 2008 22.024 2009 21.790000000000006 2010 21.558000000000007 2011 21.326999999999998 2012 21.098 2013 20.867000000000004 2014 20.634 2015 20.397999999999996 2016 20.159999999999997 2017 19.92 2018 19.679000000000002 2019 19.435000000000002 2020 19.189999999999998 2021 18.944000000000003 2022 18.695999999999998 2023 18.447999999999993