Year Percent 1950 5.57051 1955 4.91894 1960 4.65618 1965 4.56411 1970 4.51616 1975 4.53347 1980 4.66894 1985 4.76863 1990 5.15712 1995 5.26495 2000 5.30798 2005 5.24629 2010 5.12394 2015 5.20554 2020 5.36229 2025 5.66257 2030 6.11695 2035 6.76124 2040 7.53963 2045 8.48536 2050 9.41163 2055 10.30443 2060 11.1722 2065 12.13058 2070 13.34449 2075 14.75529 2080 16.08967 2085 17.34556 2090 18.57231 2095 19.81453 2100 21.08843