Year Percent 1950 10.59647 1955 11.12767 1960 10.86452 1965 13.17586 1970 12.70068 1975 10.18436 1980 8.32097 1985 7.95239 1990 7.75066 1995 8.17428 2000 7.63934 2005 6.66039 2010 5.14293 2015 5.14987 2020 4.48054 2025 4.55847 2030 4.3127 2035 4.29797 2040 4.23772 2045 4.17518 2050 3.88425 2055 3.62371 2060 3.50292 2065 3.48826 2070 3.50903 2075 3.50042 2080 3.4625 2085 3.42317 2090 3.4294 2095 3.50732 2100 3.61962