Year Percent 1950 26.34405 1955 26.25506 1960 22.912 1965 22.76404 1970 22.39893 1975 22.19683 1980 23.71607 1985 22.0996 1990 23.33421 1995 24.52961 2000 25.97802 2005 27.53441 2010 26.93838 2015 26.58267 2020 25.65048 2025 24.77925 2030 23.8735 2035 22.88847 2040 22.75771 2045 22.72811 2050 22.95759 2055 23.24706 2060 23.23731 2065 22.97847 2070 22.64648 2075 22.49723 2080 22.47826 2085 22.46397 2090 22.35093 2095 22.12612 2100 21.88206