"By the mid-1960s, advertisers no longer thought of country radio stations as only being listened to by country folk. During the 1950s, it looked as though country would not survive the popularity of rock and Top 40 formatting, but the introduction of the "Nashville Sound" - typified by the now-classic recordings of Patsy Cline, - proved that crossover hit making was possible. By the mid-1970s, country had its place in radio, with more than 1,000 stations playing country format. Country had become suburban-it had given a voice to adult problems, such as infidelity, boss hating, and the like, whereas pop music seemed stuck in teenaged concerns. Country radio listeners were therefore older, and were nearly always white. By the 1990s, one survey determined that country stations were number one in 57 of the top 100 radio markets in the United States."