Replying to The development of freestyle skiing?

Reflecting on extreme and any other sports by that matter, how quickly has 'freestyle' skiing developed and progressed with regards to size, influence and economic power in the recent years. How long did it take the first freestyle skiers to the top professionals today to develop the sport into a billion dollar industry, specifically in contrast with snowboarding? Does anyone have a time line or list of important breakthroughs in the sport that contribute to its progression and strength?