Year Percent 1950 29.61357 1955 29.38621 1960 29.00749 1965 29.41176 1970 30.06956 1975 29.80928 1980 29.12786 1985 28.60006 1990 29.43879 1995 32.87843 2000 32.47219 2005 31.361 2010 29.3203 2015 29.06273 2020 29.58792 2025 30.16735 2030 29.56561 2035 28.40302 2040 27.63774 2045 27.14815 2050 26.81917 2055 26.23574 2060 25.57442 2065 24.9226 2070 24.33939 2075 23.87917 2080 23.54407 2085 23.26864 2090 22.98787 2095 22.68649 2100 22.3923