Year % of total population 1960 36.3147660816548 1961 35.5352166361879 1962 34.619110930923 1963 33.6300744381094 1964 32.5755025670418 1965 31.5179794179552 1966 30.5147166960541 1967 29.5908343393675 1968 28.7140137491727 1969 27.8823471788382 1970 27.1298991167164 1971 26.4631115934992 1972 25.8055156996885 1973 25.1880971432005 1974 24.6718449414217 1975 24.2191484235918 1976 23.9096240650538 1977 23.7183041324758 1978 23.5947799240533 1979 23.5533170031304 1980 23.5875498745455 1981 23.6436365364791 1982 23.7533065326929 1983 23.9175702711688 1984 24.0155626058263 1985 24.0264380903278 1986 23.9410778164199 1987 23.8073987313082 1988 23.6672069724556 1989 23.4930345722303 1990 23.240688412292 1991 22.9502304909953 1992 22.6831540862027 1993 22.3905138424188 1994 22.019320430153 1995 21.6073914130866 1996 21.254370323073 1997 20.8983935489927 1998 20.4818049212385 1999 20.0551792061518 2000 19.6140391747232 2001 19.119162803073 2002 18.5565303553139 2003 17.9699153885663 2004 17.3773876371856 2005 16.8123244792886 2006 16.3116264082345 2007 15.842273727738 2008 15.4285845600463 2009 15.1066185318893 2010 14.8161812993278 2011 14.5243654546699 2012 14.2535478603512 2013 14.012342151877 2014 13.8147033986574 2015 13.6617252016904 2016 13.5656022492811 2017 13.5032127416856 2018 13.4093525853055 2019 13.2949589434401 2020 13.1987860865651 2021 13.1344589822837 2022 13.1489482191545 2023 13.2026138904749