Year Percent 1950 27.68026 1955 27.758 1960 28.60632 1965 28.1915 1970 26.59664 1975 25.72893 1980 25.99423 1985 28.74449 1990 29.95492 1995 31.80299 2000 35.2353 2005 38.86811 2010 39.42899 2015 35.84386 2020 32.92882 2025 30.98093 2030 30.04253 2035 30.21406 2040 30.14136 2045 29.48712 2050 28.16166 2055 26.47387 2060 25.43532 2065 25.02799 2070 24.99233 2075 24.92334 2080 24.54335 2085 23.90924 2090 23.29074 2095 22.92016 2100 22.81431