Year Percent 1950 29.5211 1955 27.48582 1960 26.04446 1965 25.79037 1970 25.78793 1975 28.05917 1980 30.90522 1985 32.70367 1990 32.05405 1995 31.76835 2000 31.55106 2005 32.46137 2010 33.13447 2015 32.04824 2020 29.66516 2025 26.38406 2030 24.70288 2035 24.69204 2040 25.00377 2045 24.49464 2050 23.2732 2055 22.09174 2060 21.64992 2065 21.80886 2070 22.11655 2075 22.17288 2080 21.89464 2085 21.51633 2090 21.32872 2095 21.40726 2100 21.5927