Year Percent 1950 19.35004 1955 18.92876 1960 19.25775 1965 19.34385 1970 19.37421 1975 19.34008 1980 19.26017 1985 18.90758 1990 18.57495 1995 18.20236 2000 17.80503 2005 18.19543 2010 18.24433 2015 17.88682 2020 16.95099 2025 16.21057 2030 15.60179 2035 14.99584 2040 14.34301 2045 13.66508 2050 12.98347 2055 12.36175 2060 11.7981 2065 11.2432 2070 10.72477 2075 10.21671 2080 9.73979 2085 9.30047 2090 8.90139 2095 8.5178 2100 8.14472