Year Percent 1950 3.19589 1955 3.36076 1960 3.70165 1965 3.64755 1970 3.85093 1975 4.45247 1980 4.60169 1985 4.81707 1990 5.59234 1995 6.23296 2000 7.05022 2005 8.21755 2010 9.64509 2015 11.50458 2020 13.71016 2025 16.59498 2030 19.60621 2035 22.15069 2040 24.33992 2045 26.41725 2050 28.28835 2055 30.0032 2060 31.63966 2065 33.06889 2070 34.09008 2075 35.36749 2080 36.45697 2085 37.29833 2090 38.03105 2095 38.6658 2100 39.22181