Year Percent 1950 15.86389 1955 15.78277 1960 15.69032 1965 15.4465 1970 15.15885 1975 14.74524 1980 14.36838 1985 14.33462 1990 14.46541 1995 15.67195 2000 16.72982 2005 17.54353 2010 18.23966 2015 19.14069 2020 20.08354 2025 21.63906 2030 23.34353 2035 24.5899 2040 25.29392 2045 25.33482 2050 25.27761 2055 25.6611 2060 26.14642 2065 26.55119 2070 26.64961 2075 26.37333 2080 26.08612 2085 25.87734 2090 25.71914 2095 25.54236 2100 25.29413