Year % of total population 1960 60.54 1961 59.557 1962 58.565 1963 57.566 1964 56.559 1965 55.55 1966 54.535 1967 53.516 1968 52.493 1969 51.47 1970 50.445 1971 49.281 1972 48.032 1973 46.79 1974 45.549 1975 44.315 1976 43.085 1977 41.868 1978 40.658 1979 39.639 1980 38.842 1981 38.054 1982 37.27 1983 36.494 1984 35.723 1985 34.962 1986 34.206999999999994 1987 33.459999999999994 1988 32.72 1989 32.358000000000004 1990 32.417 1991 32.477000000000004 1992 32.536 1993 32.596000000000004 1994 32.655 1995 32.715 1996 32.775000000000006 1997 32.834 1998 32.894000000000005 1999 32.95399999999999 2000 33.013999999999996 2001 33.081 2002 33.172 2003 33.263000000000005 2004 33.354 2005 33.364999999999995 2006 33.294 2007 33.223 2008 33.152 2009 33.158 2010 33.242999999999995 2011 33.259 2012 33.135999999999996 2013 33.013999999999996 2014 32.891999999999996 2015 32.769999999999996 2016 32.634 2017 32.483999999999995 2018 32.321 2019 32.144999999999996 2020 31.953999999999994 2021 31.751000000000005 2022 31.534999999999997 2023 31.305999999999997