Year Percent 1950 28.41385 1955 28.76549 1960 25.89011 1965 23.92364 1970 22.41696 1975 22.18261 1980 25.7724 1985 26.6014 1990 26.27232 1995 26.61381 2000 26.76835 2005 28.81409 2010 31.10143 2015 30.49335 2020 28.74775 2025 26.80199 2030 25.57039 2035 25.74531 2040 25.93099 2045 25.17654 2050 23.81147 2055 23.07386 2060 22.90764 2065 23.2609 2070 23.64891 2075 23.68236 2080 23.36637 2085 22.90595 2090 22.59242 2095 22.52467 2100 22.58698