From the 1970s, the government promoted adult education in Mandarin, required Mandarin for official purposes, and encouraged its increased use in broadcasting. Over a 40-year period, these policies succeeded in spreading the use and prestige of Mandarin through society at the expense of the other languages. They also aggravated social divisions, as Mandarin speakers found it difficult to find jobs in private companies but were favored for government positions. From the 1990s, were offered in elementary and middle schools, first in Yilan county, then in other areas governed by elected Democratic Progressive Party (DPP) politicians, and finally throughout the island.