Year Percent 1950 39.23546 1955 32.29565 1960 23.80854 1965 20.62378 1970 22.40974 1975 31.96704 1980 39.26327 1985 43.96502 1990 41.25946 1995 36.10988 2000 29.40772 2005 29.95346 2010 35.06089 2015 36.03811 2020 33.91024 2025 28.07201 2030 23.06397 2035 21.21823 2040 21.95561 2045 23.9693 2050 25.08803 2055 24.58677 2060 23.27489 2065 22.29568 2070 22.0905 2075 22.55614 2080 23.14873 2085 23.37068 2090 23.07978 2095 22.51072 2100 22.00524