Year % of total population 1960 30.40056223538 1961 29.7760285516499 1962 29.0620216679148 1963 28.3659428194038 1964 27.7216355101259 1965 27.1443057181449 1966 26.6385393557731 1967 26.1505402250761 1968 25.6649239322916 1969 25.1732604272514 1970 24.6152874308522 1971 24.0048074504859 1972 23.4021454660741 1973 22.8655305946606 1974 22.4039115878306 1975 22.0112502356004 1976 21.6645667205161 1977 21.3373559228896 1978 20.9893527480852 1979 20.6292386454804 1980 20.308194428694 1981 20.0217068582443 1982 19.7734511103593 1983 19.5896273538928 1984 19.4797969374696 1985 19.410679953286 1986 19.3485690060688 1987 19.307865401816 1988 19.3362500395477 1989 19.3602666304359 1990 19.3167212970103 1991 19.2445372362259 1992 19.1769396252093 1993 19.1347756535195 1994 19.0913610914043 1995 19.0287949571873 1996 18.9306007734864 1997 18.773118570879 1998 18.5544143453113 1999 18.3338428041013 2000 18.1527929030686 2001 18.0015526206859 2002 17.8684152612907 2003 17.715815245342 2004 17.5455099623365 2005 17.3598775159543 2006 17.1663406440692 2007 16.9771468883877 2008 16.8042085685859 2009 16.6655053602719 2010 16.5571237629868 2011 16.4867971773698 2012 16.4429029683727 2013 16.4228645593116 2014 16.4027634106356 2015 16.3579045457208 2016 16.2889413506541 2017 16.2000526675114 2018 16.070388313869 2019 15.8772381564443 2020 15.6613258273671 2021 15.4286440442833 2022 15.1728770072547 2023 14.91327748419