Year Percent 1950 27.09872 1955 27.3876 1960 27.64547 1965 27.85851 1970 26.69705 1975 26.86725 1980 26.9588 1985 26.82534 1990 26.67321 1995 27.28495 2000 27.92612 2005 29.11302 2010 30.46345 2015 30.22379 2020 30.64427 2025 29.97373 2030 30.21236 2035 30.78093 2040 30.54122 2045 30.46748 2050 29.69052 2055 29.1923 2060 28.73823 2065 28.36183 2070 28.00133 2075 27.58662 2080 27.10539 2085 26.57782 2090 26.04224 2095 25.52199 2100 25.01097