Year % of total population 1960 40.248 1961 39.98 1962 39.796 1963 39.613 1964 39.43 1965 39.247 1966 39.064 1967 38.882 1968 38.7 1969 38.519 1970 38.337 1971 38.087 1972 37.768 1973 37.45 1974 37.133 1975 36.817 1976 36.502 1977 36.189 1978 35.876999999999995 1979 35.565 1980 35.254999999999995 1981 34.896 1982 34.489000000000004 1983 34.084 1984 33.681 1985 33.281000000000006 1986 32.882999999999996 1987 32.486999999999995 1988 32.093999999999994 1989 31.703999999999994 1990 31.316000000000003 1991 30.671000000000006 1992 29.777 1993 28.900000000000006 1994 28.037999999999997 1995 27.191000000000003 1996 26.36 1997 25.546999999999997 1998 24.75 1999 23.97 2000 23.205 2001 22.17 2002 20.887 2003 19.659000000000006 2004 18.486000000000004 2005 17.370000000000005 2006 16.364000000000004 2007 15.460999999999999 2008 14.597999999999999 2009 13.712000000000003 2010 12.866 2011 12.120999999999995 2012 11.412000000000006 2013 10.813000000000002 2014 10.310000000000002 2015 9.826999999999998 2016 9.364999999999995 2017 8.923000000000002 2018 8.510000000000005 2019 8.123999999999995 2020 7.763999999999996 2021 7.427999999999997 2022 7.114000000000004 2023 6.820999999999998