In early 1999, before the crackdown, the government estimated practitioners in the range of 70 million to 100 million. It was widely reported by different media. So this is one of the reasons--they surpassed the 33 million Communist Party members at that time--and it's because of their jealousy; they wanted control and authority. This was one of the reasons they cracked down. So the number in China is 70 million to 100 million.
On May 31st, 2006. See this statement in context.