Year Percent 1950 3.64716 1955 3.30915 1960 2.67052 1965 2.28301 1970 2.62407 1975 2.61882 1980 2.15466 1985 2.16819 1990 2.32341 1995 2.55238 2000 2.9354 2005 3.58959 2010 3.45654 2015 4.46399 2020 6.80045 2025 9.03364 2030 12.43645 2035 15.67696 2040 17.89243 2045 18.88551 2050 18.92821 2055 19.35109 2060 20.43595 2065 21.22796 2070 22.21219 2075 23.47183 2080 24.86086 2085 25.90571 2090 26.75988 2095 27.60309 2100 28.50378