Year Percent 1950 13.97306 1955 14.31332 1960 12.73954 1965 13.3373 1970 13.65009 1975 13.92277 1980 13.9827 1985 14.2504 1990 14.03077 1995 15.38254 2000 13.88644 2005 11.27062 2010 9.5593 2015 8.85019 2020 8.06065 2025 7.67754 2030 7.08069 2035 6.45655 2040 5.93078 2045 5.57642 2050 5.36712 2055 5.23383 2060 5.10508 2065 4.96838 2070 4.85229 2075 4.79254 2080 4.79099 2085 4.81486 2090 4.82636 2095 4.80916 2100 4.77887