Snowboarding has mushroomed in popularity since the early 1990s. In Belfast, with its industrial boom, the working population mushroomed, growing fivefold in fifty years. Unemployment mushroomed, and private investment withered. It was the beginning of a dispute which mushroomed rapidly. In the republican China between 1912 and 1949 folk religious sects mushroomed and expanded rapidly. Subway ridership was spiraling downwards, while private express buses mushroomed, exacerbating Transit Authority's (TA) problems. In addition, multiplexes have mushroomed in most cities, changing the revenue patterns. Localist political groups led by youngsters mushroomed after the protests. Slums have mushroomed around the park as well. As the formal housing was built, shacks mushroomed a. Many smaller Orthodox chapels have mushroomed in the area. Individual and private industrial enterprises and enterprises have mushroomed with investment from outside mainland China. In 2008 the RCs "nearly doubled" and their numbers mushroomed since then. That was the beginning of a word of mouth situation which gradually mushroomed. Burundi and Angola also supported the growing rebellion, which mushroomed into the First Congo War.