Year % of total population 1960 38.401808392620936 1961 37.91897062837137 1962 37.4229774845441 1963 36.861083503791484 1964 36.30018908942554 1965 35.74062705741029 1966 35.182518367639624 1967 34.63063872147607 1968 34.12460143063446 1969 33.6930295845929 1970 33.27172421530641 1971 32.87153739026875 1972 32.530814421020246 1973 32.21220685419699 1974 31.905051078994248 1975 31.64488412882169 1976 31.4161676702291 1977 31.166851194317825 1978 30.91556595066432 1979 30.665646423197586 1980 30.41720660840604 1981 30.172278504495587 1982 30.01415250426755 1983 29.902562033127104 1984 29.831284323228612 1985 29.775096131650375 1986 29.682615622827335 1987 29.51156952418881 1988 29.349605905864117 1989 29.237996962603532 1990 29.08725931175763 1991 28.912992000771546 1992 28.75443397050274 1993 28.5896229211651 1994 28.408878598111507 1995 28.22766922662845 1996 28.046418062695693 1997 27.869999913002477 1998 27.696819792170455 1999 27.517998562709614 2000 27.325458869075995 2001 27.109303022316805 2002 26.86567831703958 2003 26.61485665101858 2004 26.369089393589878 2005 26.126041351206442 2006 25.888000331241606 2007 25.658647519774803 2008 25.431645993408225 2009 25.203646061179292 2010 24.972585705565844 2011 24.745800891600588 2012 24.530247990245684 2013 24.32339238451875 2014 24.122426963066435 2015 23.908306308996153 2016 23.691837293505955 2017 23.470464425974374 2018 23.24395266954511 2019 23.00284256590409 2020 22.768376883431095 2021 22.524035740419695 2022 22.28035107956284 2023 22.033235103818186