sentences:  This statistic is supported by mining company records showing that about 57 percent of the UVX workers were Mexican nationals in 1931 and that foreign-born and Spanish-surnamed workers accounted for about 77 percent of the UVX work force.The ratio of females to males also varied greatly over time in Jerome.Census data from 1900 through 1950 show a gradual rise in the percentage of female residents, who accounted for only 22 percent of the population at the turn of the century but about 50 percent by mid-century.