For example, the average age of the onset of menstrual periods in girls was 15 in 1900. By the 1990s, this average had dropped to 12 and a half years of age.uberty facts. 1  Puberty is the period of sexual maturation and achievement of fertility. 2  The time when puberty begins varies greatly among individuals; however, puberty usually occurs in girls between the ages of 10 and 14 and between the ages of 12 and 16 in boys.
Herbert Hoover was the president of the U.S. when the great depression began in 1929.
Introduction. The Great Depression in the United States began on October 29, 1929, a day known forever after as âBlack Tuesday,â when the American stock marketâwhich had been roaring steadily upward for almost a decadeâcrashed, plunging the country into its most severe economic downturn yet.