Year Percent 1950 27.06381 1955 27.61591 1960 28.22341 1965 28.41061 1970 27.75682 1975 28.1587 1980 29.40338 1985 31.28675 1990 32.37255 1995 28.78036 2000 27.79715 2005 25.47875 2010 26.31729 2015 29.34722 2020 30.77975 2025 29.8342 2030 27.24836 2035 24.7917 2040 22.3104 2045 21.67942 2050 22.10945 2055 21.65558 2060 20.7832 2065 19.72011 2070 18.93198 2075 18.70905 2080 18.96212 2085 19.26705 2090 19.28817 2095 19.06202 2100 18.81913