In the 1960s, the development of LP records and improvements in recording technology led to the pursuit of diverse voice tones. Open auditions were also held to recruit musicians to perform at the U.S. army clubs. Since South Korea was impoverished after the Korean War, skilled Korean singers regarded performing for the U.S. troops as a good means to earn money. Many singers sang for the American troops, usually in dedicated clubs, the number of which rose to 264. They performed various genres like country music, blues, jazz and rock & roll. The South Korean economy started blooming and popular music followed the trend, spread by the first commercial radio stations. Korean cinema also began to develop and Korean musicians began performing to wider audiences.