Year % of total population 1960 28.809368026257896 1961 29.378585812126335 1962 29.69855662763954 1963 30.04600575742501 1964 30.42113645945566 1965 30.818842588740996 1966 31.24445529951247 1967 31.697051741161104 1968 32.179315472983575 1969 32.68803464793324 1970 33.22848229598498 1971 33.79771211807197 1972 34.000902532089185 1973 34.014468155795456 1974 34.04311585765171 1975 34.08444211603682 1976 34.13829253363086 1977 34.2012495300836 1978 34.28014370596897 1979 34.37554243922804 1980 34.49253253176124 1981 34.62723806091483 1982 34.52290598092767 1983 34.32895026625727 1984 34.158839546484174 1985 34.00939323896422 1986 33.8753281474723 1987 33.75625761955801 1988 33.662030863629525 1989 33.5921448038245 1990 33.551704990522055 1991 33.314499688374696 1992 33.00563692760272 1993 32.722592468390005 1994 32.46604231916581 1995 32.23290276336951 1996 32.02157441196237 1997 31.825925496192937 1998 31.646840030549928 1999 31.488140339867886 2000 31.34849743911929 2001 31.232610923632738 2002 31.036556140518968 2003 30.805294649230287 2004 30.594548877190224 2005 30.398336482145698 2006 30.22336181491008 2007 30.070041170063817 2008 29.941999008872145 2009 29.837176024252 2010 29.74776756221883 2011 29.671816819532776 2012 29.61939878303761 2013 29.58211605253579 2014 29.56344426295433 2015 29.5685718137699 2016 29.69928172581501 2017 30.21303595050988 2018 31.315173552109655 2019 32.55304498533965 2020 33.431437541551205 2021 34.11576019135126 2022 34.34099143740361 2023 34.052926957120754