Year Percent 1950 27.10343 1955 26.97211 1960 26.87783 1965 26.46151 1970 26.30901 1975 26.83155 1980 27.7347 1985 29.33277 1990 30.70214 1995 31.41965 2000 31.90983 2005 32.06024 2010 32.33003 2015 32.20912 2020 31.25086 2025 30.28692 2030 29.16689 2035 28.40213 2040 27.90142 2045 27.26743 2050 26.43347 2055 25.37917 2060 24.44273 2065 23.68412 2070 23.06948 2075 22.52429 2080 22.00778 2085 21.51302 2090 21.08236 2095 20.74076 2100 20.48355