Year % of total population 1960 44.089 1961 43.665 1962 43.242 1963 42.819 1964 42.397 1965 41.978 1966 41.559 1967 41.141 1968 40.724 1969 40.309 1970 39.888 1971 39.461 1972 39.035 1973 38.612 1974 38.19 1975 37.769 1976 37.35 1977 36.934 1978 36.52 1979 36.107 1980 35.809 1981 35.628 1982 35.447 1983 35.266000000000005 1984 35.084999999999994 1985 34.905 1986 34.726 1987 34.547 1988 34.367999999999995 1989 34.19 1990 34.162000000000006 1991 34.287000000000006 1992 34.413 1993 34.539 1994 34.665000000000006 1995 34.791 1996 34.917 1997 35.044 1998 35.17100000000001 1999 35.298 2000 35.425 2001 35.33 2002 34.919 2003 34.510999999999996 2004 34.104 2005 33.635000000000005 2006 33.105000000000004 2007 32.57899999999999 2008 32.057 2009 31.540000000000006 2010 31.089 2011 30.641999999999996 2012 30.322000000000003 2013 30.046999999999997 2014 29.772999999999996 2015 29.5 2016 29.221000000000004 2017 28.938000000000002 2018 28.649 2019 28.355999999999995 2020 28.058000000000007 2021 27.754999999999995 2022 27.447999999999993 2023 27.135999999999996