Year % of total population 1960 36.2642995984539 1961 36.428063279863 1962 36.4060163693357 1963 36.2121910260362 1964 35.8867915804329 1965 35.4651740502556 1966 34.9722437830987 1967 34.4268157814435 1968 33.8407378167632 1969 33.2284331027813 1970 32.5982640836936 1971 31.972327967185 1972 31.3814569744423 1973 30.8267598903172 1974 30.2940198254608 1975 29.7739589721767 1976 29.2641121453999 1977 28.7704364322391 1978 28.3100886893 1979 27.9032292626481 1980 27.5624889173961 1981 27.2540805960326 1982 26.9653482263706 1983 26.7264501413663 1984 26.5246863475073 1985 26.3405896576704 1986 26.1706567658884 1987 26.0084543336646 1988 25.8482874710834 1989 25.695950538957 1990 25.5536522745906 1991 25.3949090653072 1992 25.124927210433 1993 24.7631656696646 1994 24.4108065616588 1995 24.0619049766203 1996 23.7032467409369 1997 23.322403854121 1998 22.912496075898 1999 22.4932659852964 2000 22.0792026836164 2001 21.6866356535269 2002 21.3213388817155 2003 20.9946524994406 2004 20.7263351015856 2005 20.4845976815345 2006 20.233026899272 2007 19.9717528652643 2008 19.7346177509021 2009 19.5381046988032 2010 19.3354187663618 2011 19.0984950648002 2012 18.8872767654397 2013 18.7281872022122 2014 18.6171407760906 2015 18.5247170000308 2016 18.4250316021688 2017 18.3323108352123 2018 18.2554720886461 2019 18.2183103953705 2020 18.2062562843029 2021 18.1815647952524 2022 18.095146970295 2023 17.9283765200895