Year % of total population 1960 41.599 1961 41.412 1962 41.224 1963 41.037 1964 40.85 1965 40.663 1966 40.477 1967 40.291 1968 40.105 1969 39.919 1970 39.734 1971 39.024 1972 38.2 1973 37.386 1974 36.577 1975 35.775999999999996 1976 34.982 1977 34.19799999999999 1978 33.42100000000001 1979 32.653999999999996 1980 31.894000000000005 1981 31.147000000000006 1982 30.586 1983 30.075000000000003 1984 29.566999999999993 1985 29.066999999999993 1986 28.569999999999993 1987 28.078999999999994 1988 27.592 1989 27.111999999999995 1990 26.635999999999996 1991 26.323999999999998 1992 26.173000000000002 1993 26.022999999999996 1994 25.873000000000005 1995 25.723 1996 25.573999999999998 1997 25.382000000000005 1998 25.144999999999996 1999 24.911 2000 24.677000000000007 2001 24.444999999999993 2002 24.215000000000003 2003 24.052999999999997 2004 23.959000000000003 2005 23.866 2006 23.772999999999996 2007 23.680000000000007 2008 23.587000000000003 2009 23.495000000000005 2010 23.403000000000006 2011 23.311000000000007 2012 23.218999999999994 2013 23.173000000000002 2014 23.138999999999996 2015 23.104 2016 23.069999999999993 2017 23.022999999999996 2018 22.962999999999994 2019 22.891000000000005 2020 22.805999999999997 2021 22.708 2022 22.599000000000004 2023 22.477000000000004