Year Percent 1950 29.90336 1955 28.29732 1960 28.26446 1965 28.18313 1970 30.54707 1975 33.37011 1980 34.42312 1985 34.86471 1990 32.05036 1995 29.21866 2000 27.5477 2005 26.33708 2010 25.73596 2015 26.32973 2020 25.70621 2025 24.74705 2030 24.37608 2035 23.78363 2040 23.93941 2045 24.22353 2050 24.07486 2055 23.84551 2060 23.49612 2065 23.19257 2070 23.02102 2075 22.93126 2080 22.81142 2085 22.59594 2090 22.32852 2095 22.07327 2100 21.86231