Year Percent 1950 28.56932 1955 28.84271 1960 28.71955 1965 28.2551 1970 26.81511 1975 26.38931 1980 25.97811 1985 25.97677 1990 26.2577 1995 26.94501 2000 27.77852 2005 27.71 2010 27.95322 2015 28.61671 2020 29.31102 2025 29.84228 2030 30.19625 2035 30.47549 2040 30.62814 2045 30.82261 2050 30.99574 2055 31.03588 2060 30.97537 2065 30.87314 2070 30.75701 2075 30.59669 2080 30.40398 2085 30.17862 2090 29.92464 2095 29.64874 2100 29.34779