Year Percent 1950 16.25326 1955 17.76244 1960 18.57811 1965 17.77671 1970 16.96119 1975 16.52948 1980 17.36034 1985 18.3087 1990 19.09027 1995 20.82705 2000 22.16918 2005 26.43825 2010 30.49535 2015 32.60945 2020 32.01618 2025 28.68227 2030 26.46473 2035 24.14962 2040 24.22036 2045 23.83538 2050 22.13655 2055 21.73194 2060 21.64887 2065 22.06938 2070 22.55268 2075 22.29966 2080 21.9092 2085 21.61675 2090 21.57633 2095 21.65562 2100 21.68566