Year % of total population 1960 34.8904830933008 1961 34.9625603628614 1962 34.9399307620831 1963 34.8415071689846 1964 34.7109514026056 1965 34.515805292524 1966 34.2828868130547 1967 34.0366485428392 1968 33.6507487429953 1969 33.1594840093048 1970 32.6327347066534 1971 32.0918072861848 1972 31.6055662050471 1973 31.1806059122115 1974 30.6761860080546 1975 30.067937056764 1976 29.5208279888942 1977 28.9763009466552 1978 28.3834359531571 1979 27.8964636289976 1980 27.5272383172043 1981 27.1727549137655 1982 26.8727390056646 1983 26.6782354938083 1984 26.4740181035688 1985 26.214775796587 1986 25.9222048266538 1987 25.5628829524555 1988 25.2364289672751 1989 25.0599210011006 1990 24.9637772797766 1991 24.8413704354028 1992 24.8208219702407 1993 24.8585333694538 1994 24.7174846792838 1995 24.4287043159582 1996 24.1416530273672 1997 23.865924958219 1998 23.5938895674207 1999 23.4010863535836 2000 23.2875130568247 2001 23.1820444681284 2002 23.0234400517029 2003 22.7768365188526 2004 22.4749923467774 2005 22.0544493205197 2006 21.5287244241056 2007 21.0900648703075 2008 20.8764143965504 2009 20.8856322370887 2010 20.91646169263 2011 20.8197486321341 2012 20.6899506043221 2013 20.5754503131708 2014 20.428606091682 2015 20.1761314808969 2016 19.8698441496152 2017 19.5348512362062 2018 19.160013146487 2019 18.8547139556704 2020 18.7095173030717 2021 18.6286740383707 2022 18.4862636883763 2023 18.3073842616338