Year % of total population 1960 32.7789184310863 1961 32.9446070134826 1962 32.9613497590104 1963 32.9053324651007 1964 32.8279256772823 1965 32.7196211522805 1966 32.5793039373317 1967 32.4427312148936 1968 32.3193730127072 1969 32.1498984783871 1970 31.9055133556806 1971 31.6398127426138 1972 31.3496147391298 1973 30.9767405501775 1974 30.5243965121736 1975 30.0554236764674 1976 29.5664988816463 1977 28.9877287918466 1978 28.3596742849353 1979 27.7579804486149 1980 27.1991719538283 1981 26.6817217177945 1982 26.1578932995074 1983 25.6208485735414 1984 25.1097616110563 1985 24.6443968534023 1986 24.2125429392526 1987 23.8051608896694 1988 23.4835654502018 1989 23.2965229898418 1990 23.2611460243655 1991 23.1808286939421 1992 23.0770297765432 1993 23.080233547917 1994 23.0817115292495 1995 23.0689897609974 1996 23.0409224189896 1997 23.0078535917192 1998 22.9627269396364 1999 22.8890175501797 2000 22.7749265550029 2001 22.6047758131119 2002 22.3786074170649 2003 22.1196654378758 2004 21.8456202068477 2005 21.5462058115347 2006 21.2812722937776 2007 21.1215508064207 2008 21.0298554881376 2009 20.9523421080245 2010 20.870348685451 2011 20.7676931044407 2012 20.6296215130793 2013 20.4402441534304 2014 20.2260203646497 2015 20.0301486301325 2016 19.8651330171863 2017 19.7361433543924 2018 19.5722312952333 2019 19.3069759150673 2020 19.0681692154534 2021 18.8906428265439 2022 18.7042823171748 2023 18.5143664538137