Year % of total population 1960 3.16992321122278 1961 3.20476293533288 1962 3.23490176002435 1963 3.2613622077449 1964 3.2842802126342 1965 3.30359330192082 1966 3.3205761457987 1967 3.33559571607755 1968 3.34842685750845 1969 3.35930424027201 1970 3.36799985595181 1971 3.37559897642697 1972 3.38147125716891 1973 3.38477441964073 1974 3.38225852151195 1975 3.37478074762856 1976 3.36786901224082 1977 3.362666184216 1978 3.35628857633051 1979 3.34704675499042 1980 3.33438641626544 1981 3.31743987890017 1982 3.29709222664385 1983 3.27419738468604 1984 3.24949546786597 1985 3.22347611549237 1986 3.19631576913284 1987 3.16854391252086 1988 3.1299590906228 1989 3.08729680196288 1990 3.05185862944719 1991 2.9694915183749 1992 2.84221341425045 1993 2.77490590537688 1994 2.75544145951298 1995 2.73376665700541 1996 2.71146009675541 1997 2.6854679917919 1998 2.65965831362136 1999 2.63813052665526 2000 2.62060903758715 2001 2.60803217199201 2002 2.60076330058035 2003 2.59475017140571 2004 2.58352615794969 2005 2.56614127130494 2006 2.54600081057227 2007 2.52421458645962 2008 2.50281578134202 2009 2.48413964934637 2010 2.46768644916442 2011 2.45450592266616 2012 2.44948555007781 2013 2.45067393581864 2014 2.45872884504632 2015 2.48510115932566 2016 2.52007525162761 2017 2.55055074867361 2018 2.57990777876988 2019 2.60792918573804 2020 2.6158408087602 2021 2.59659193554559 2022 2.570008338111 2023 2.55322072457453