    Sentence 1: World demand increased with the growth  of the motor-car and electrical industries, ond sky-  rocketed during World War I. By 1920, Malaya was  producing 53 percent of the world's rubber, which had  overtaken tin as its main source of income.    Sentence 2: In 1920 Malaya produced the majority of  rubber in the world, beating out tin for how much  money it made the country.