Year % of total population 1960 30.9537446101427 1961 30.9032992287686 1962 30.7224819032039 1963 30.601567443519 1964 30.7218735506281 1965 30.9456489462737 1966 31.0213259244364 1967 30.9794777235798 1968 30.9193407602246 1969 30.931221844632 1970 31.0122675108825 1971 31.0661390174503 1972 31.0554784707886 1973 31.0633902918741 1974 31.0851730258704 1975 31.049588186146 1976 30.9616444308647 1977 30.8550520538004 1978 30.7127422160952 1979 30.5560461565358 1980 30.4325929184726 1981 30.316796977366 1982 30.1757469549828 1983 29.9983328068766 1984 29.7220712755423 1985 29.3440326501832 1986 28.9441882975632 1987 28.5339101232319 1988 28.0966572613728 1989 27.6288000982972 1990 27.1017648175253 1991 26.5648768711636 1992 26.0385753522805 1993 25.4753927292213 1994 24.8430106499766 1995 24.1557437640418 1996 23.508121488507 1997 22.9354422207876 1998 22.4522632790628 1999 22.0693287998922 2000 21.7261012050968 2001 21.3729081451171 2002 21.0835698461132 2003 20.9200104579654 2004 20.7715017617386 2005 20.5787103343662 2006 20.3654877737625 2007 20.2854053617638 2008 20.4440870835175 2009 20.7521346817659 2010 21.1021452796223 2011 21.3799710903353 2012 21.5203360681776 2013 21.5379098646453 2014 21.4750979924462 2015 21.3611823154213 2016 21.2000752790494 2017 20.9914763728601 2018 20.7463346314319 2019 20.4581926663275 2020 20.1778202263229 2021 19.9131720159486 2022 19.5842275754147 2023 19.1909050829114