Year Percent 1950 27.11817 1955 27.09456 1960 26.77527 1965 26.68711 1970 27.91786 1975 29.90666 1980 32.07767 1985 33.19462 1990 34.28719 1995 34.57909 2000 33.9278 2005 31.43335 2010 29.79686 2015 29.65129 2020 28.64605 2025 28.76715 2030 27.82053 2035 25.16264 2040 23.18104 2045 21.38436 2050 20.74913 2055 20.89058 2060 20.94108 2065 20.64733 2070 20.11758 2075 19.72567 2080 19.69616 2085 19.97312 2090 20.31621 2095 20.47437 2100 20.3976