Year Percent 1950 20.21561 1955 21.29548 1960 20.14487 1965 19.33348 1970 18.37717 1975 21.741 1980 24.08596 1985 30.19201 1990 27.49448 1995 29.10415 2000 29.59498 2005 31.4178 2010 35.30098 2015 36.00515 2020 35.35725 2025 32.48674 2030 29.42115 2035 28.64826 2040 28.55039 2045 28.51084 2050 27.17761 2055 25.1802 2060 23.47861 2065 22.64072 2070 22.50861 2075 22.43476 2080 21.88916 2085 20.98048 2090 20.16553 2095 19.77684 2100 19.78738