Year % of total population 1960 22.4205664165853 1961 21.9412138074725 1962 21.5201905406234 1963 21.1894501070067 1964 20.9895834179741 1965 20.9139874508623 1966 20.9174305122103 1967 20.952151333994 1968 20.9407319543452 1969 20.8932070818253 1970 20.8403987118853 1971 20.7960804672435 1972 20.7665013635918 1973 20.7368487576558 1974 20.7182924132936 1975 20.6945763941565 1976 20.6204320482794 1977 20.4787180144706 1978 20.2591658783946 1979 19.9533789250007 1980 19.6076283459735 1981 19.2501411425697 1982 18.8841722713966 1983 18.5683319196271 1984 18.3409796065469 1985 18.1731383865363 1986 18.0187905286758 1987 17.8847721389705 1988 17.8255323455442 1989 17.8275215632438 1990 17.9114104963785 1991 18.0972613936389 1992 18.3212461366957 1993 18.5466886864478 1994 18.7132503207873 1995 18.7796636990908 1996 18.7764864887783 1997 18.7307622309097 1998 18.6576109800917 1999 18.5600351954305 2000 18.4264793651389 2001 18.2596709348365 2002 18.0840503015232 2003 17.8903067246562 2004 17.6629346379007 2005 17.3967805961684 2006 17.1242562717061 2007 16.8951599813297 2008 16.7218199964992 2009 16.624312886655 2010 16.6283679357841 2011 16.7163961546942 2012 16.8561194597753 2013 17.023635361924 2014 17.1905518215244 2015 17.3506552235409 2016 17.5066713940689 2017 17.6340524488004 2018 17.7095426644643 2019 17.7424320978691 2020 17.7450854687151 2021 17.7140280633685 2022 17.5997812945199 2023 17.4199068872981