Year Percent 1950 29.45621 1955 28.05497 1960 27.25066 1965 27.0634 1970 29.24489 1975 31.00679 1980 32.80373 1985 34.39554 1990 34.08541 1995 32.97265 2000 30.58461 2005 27.74563 2010 25.57805 2015 24.90378 2020 24.89856 2025 24.91003 2030 24.19425 2035 23.24801 2040 22.71565 2045 22.30428 2050 22.35775 2055 22.573 2060 22.53631 2065 22.23472 2070 21.86736 2075 21.62209 2080 21.55821 2085 21.59949 2090 21.58578 2095 21.42967 2100 21.19741