Year % of cohort 1960 32.995412 1961 34.381185 1962 35.509861 1963 36.245574 1964 36.843788 1965 37.041711 1966 36.912966 1967 37.934916 1968 38.141239 1969 38.475643 1970 38.492733 1971 32.464617 1972 32.586308 1973 33.710763 1974 32.330457 1975 33.099735 1976 32.679092 1977 32.246347 1978 30.654029 1979 30.481335 1980 26.130999 1981 26.304441 1982 24.715839 1983 24.791953 1984 24.658325 1985 27.233216 1986 26.805641 1987 30.554315 1988 30.536168 1989 29.873721 1990 29.885974 1991 29.265086 1992 29.098563 1993 28.730493 1994 28.35734 1995 28.644825 1996 28.423366 1997 29.022023 1998 28.876885 1999 29.673443 2000 30.526706 2001 31.510897 2002 32.574431 2003 34.201173 2004 36.423631 2005 38.841456 2006 40.706264 2007 42.008907 2008 42.562392 2009 43.038588 2010 43.73231 2011 45.296857 2012 46.460419 2013 47.811005 2014 49.438549 2015 50.447431 2016 50.706266 2017 52.091115 2018 52.951116 2019 53.39508 2020 52.683745 2021 51.663767 2022 54.463454