Year Percent 1950 28.91348 1955 27.96461 1960 27.00978 1965 26.70428 1970 26.56763 1975 27.57474 1980 28.37583 1985 29.23847 1990 30.19918 1995 31.45782 2000 32.28347 2005 32.88191 2010 33.23154 2015 33.03556 2020 32.83546 2025 31.893 2030 30.84393 2035 30.38575 2040 30.09321 2045 29.76642 2050 29.17801 2055 28.24105 2060 27.36004 2065 26.62046 2070 25.99671 2075 25.41917 2080 24.8278 2085 24.2493 2090 23.73901 2095 23.31726 2100 22.9855