Year Percent 1950 27.78373 1955 26.46834 1960 25.84622 1965 26.05704 1970 26.46695 1975 30.71961 1980 34.47387 1985 34.18858 1990 33.42013 1995 32.73521 2000 32.19309 2005 33.33378 2010 34.28052 2015 34.76328 2020 32.59211 2025 30.60236 2030 28.60658 2035 27.10035 2040 25.43743 2045 23.9218 2050 22.94542 2055 22.08995 2060 21.57931 2065 21.41331 2070 21.33018 2075 21.21279 2080 21.04115 2085 20.9004 2090 20.86472 2095 20.90691 2100 20.95443