Year Percent 1950 31.88915 1955 32.60314 1960 36.4941 1965 34.1174 1970 32.10022 1975 32.99027 1980 32.92099 1985 35.3655 1990 33.55609 1995 32.13145 2000 31.08028 2005 32.11465 2010 34.2567 2015 33.1534 2020 29.94809 2025 26.53683 2030 23.68436 2035 24.66728 2040 27.1441 2045 28.36059 2050 27.9765 2055 26.17475 2060 25.11712 2065 25.13742 2070 25.94222 2075 26.62268 2080 26.46403 2085 25.56643 2090 24.61683 2095 24.17179 2100 24.26088