Yeah the number is increasing so fast. In fact, Chinese sating fans are also debating about the naturalization.
Here's some policy related background.
Chinese Taipei always have ladies switched from US because they reorganize dual citizenship.
China is different. In the past, Chinese skating field was not highly supported by the government. But recently to prepare for the Olympics, the policy is opened for international athletes to represent China. The ice hockey team and snowboard team also have naturalized athletes.
If an american-born athlete want to get citizenship, the only way is when he/she were born with at least one of the parents holding Chinese citizenship. The kids will be treated as dual citizenship before 18 and need to choose one citizenship because dual is not allowed for adults. So, there is the difficulty.
However, the US figure skating fields are filled with Asians. Over half of the juniors ladies in 18 US nationals are Asian and 6 out of 12 are with Chinese surnames. Most of them are second generation immigrants and their parents might have Chinese citizenship when giving birth to them. So the american-born Chinese girls are able to get citizenship. Also, because of the Olympics, the funding to elite skaters are more than enough but the ladies field are very weak. So a decent skater can switch to China with more funding and more chance to compete in international level.