As the industrial center of China with the most skilled industrial workers, Shanghai became a center for radical leftism during the 1950s and 1960s. The radical leftist Jiang Qing and her three allies, together the Gang of Four, were based in the city. During the Cultural Revolution (1966–1976), Shanghai's society was severely damaged, with 310,000 wrongful convictions involving more than 1 million people. About 11,500 people were unjustly persecuted to death. Yet, even during the most tumultuous times of the revolution, Shanghai was able to maintain economic production with positive annual growth rate.