Year Percent 1950 28.20798 1955 28.03592 1960 27.68735 1965 27.10473 1970 26.63065 1975 26.58838 1980 25.57533 1985 25.1659 1990 25.62693 1995 26.50943 2000 27.60779 2005 28.96325 2010 29.59572 2015 29.55285 2020 29.31094 2025 29.11662 2030 29.5559 2035 30.36467 2040 30.89836 2045 31.03993 2050 30.72401 2055 30.20712 2060 29.90638 2065 29.73532 2070 29.54819 2075 29.23657 2080 28.79917 2085 28.31818 2090 27.86927 2095 27.46683 2100 27.0931