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.
the primary cause of the great depression reads the first sentence of president herbert hoover s memoirs was the war of 1914 1918 and that so called great war along with the depression it spawned was the driver that eventually produced the even greater catastrophe of world war ii