Year Percent 1950 27.78225 1955 27.23403 1960 26.70442 1965 26.40538 1970 27.41386 1975 28.65334 1980 30.69452 1985 32.50322 1990 32.58074 1995 32.12106 2000 31.83375 2005 31.7952 2010 32.21 2015 32.8932 2020 32.50171 2025 30.81053 2030 28.9406 2035 27.13689 2040 25.64499 2045 24.69066 2050 23.68291 2055 22.79832 2060 22.02242 2065 21.45516 2070 21.06574 2075 20.81807 2080 20.66024 2085 20.53896 2090 20.43505 2095 20.35003 2100 20.29982