Year Percent 1950 30.27854 1955 31.71004 1960 32.64413 1965 30.87935 1970 27.42265 1975 26.2908 1980 26.71901 1985 27.98878 1990 29.07487 1995 30.59905 2000 30.95127 2005 30.43647 2010 28.34671 2015 25.30916 2020 23.01088 2025 21.42337 2030 21.54335 2035 21.4027 2040 20.68808 2045 19.73313 2050 18.48719 2055 18.07343 2060 18.42117 2065 19.1176 2070 19.62453 2075 19.72227 2080 19.48832 2085 19.2225 2090 19.20852 2095 19.47451 2100 19.8039