Year Percent 1950 29.62541 1955 27.45293 1960 26.398 1965 25.53338 1970 27.45354 1975 29.76809 1980 30.54139 1985 31.06577 1990 28.92677 1995 26.57431 2000 25.19599 2005 24.16609 2010 23.54203 2015 24.23402 2020 23.74982 2025 22.93536 2030 22.64976 2035 22.06504 2040 22.26243 2045 22.59899 2050 22.52492 2055 22.38143 2060 22.11517 2065 21.87833 2070 21.7478 2075 21.6903 2080 21.60747 2085 21.43284 2090 21.20843 2095 20.98868 2100 20.79527