Query: During what decade did adult contemporary become a very popular format for radio?
Context: On April 7, 1979, the Easy Listening chart officially became known as Adult Contemporary, and those two words have remained consistent in the name of the chart ever since. Adult contemporary music became one of the most popular radio formats of the 1980s. The growth of AC was a natural result of the generation that first listened to the more "specialized" music of the mid-late 1970s growing older and not being interested in the heavy metal and rap/hip-hop music that a new generation helped to play a significant role in the Top 40 charts by the end of the decade.