Year % of total population 1960 18.471000000000004 1961 18.058999999999997 1962 17.772000000000006 1963 17.489000000000004 1964 17.208 1965 16.932000000000002 1966 16.659999999999997 1967 16.492999999999995 1968 16.328000000000003 1969 16.164 1970 16.001000000000005 1971 15.840000000000003 1972 15.680000000000007 1973 15.522000000000006 1974 15.364000000000004 1975 15.207999999999998 1976 15.052999999999997 1977 14.900000000000006 1978 14.748000000000005 1979 14.596999999999994 1980 14.447999999999993 1981 14.299999999999997 1982 14.329999999999998 1983 14.358999999999995 1984 14.388999999999996 1985 14.418000000000006 1986 14.447999999999993 1987 14.477999999999994 1988 14.507000000000005 1989 14.537000000000006 1990 14.566999999999993 1991 14.596999999999994 1992 14.715000000000003 1993 14.843000000000004 1994 14.971999999999994 1995 15.102000000000004 1996 15.233000000000004 1997 15.364000000000004 1998 15.497 1999 15.629999999999995 2000 15.765 2001 15.900000000000006 2002 15.778000000000006 2003 15.656999999999996 2004 15.537000000000006 2005 15.418000000000006 2006 15.299999999999997 2007 15.177999999999997 2008 15.057000000000002 2009 14.936999999999998 2010 14.817999999999998 2011 14.700000000000003 2012 14.597999999999999 2013 14.498000000000005 2014 14.397999999999996 2015 14.299000000000007 2016 14.200000000000003 2017 14.096000000000004 2018 13.988 2019 13.876000000000005 2020 13.759 2021 13.638000000000005 2022 13.512 2023 13.382999999999996