That's like asking for data on the levels of corruption in a mafia family. No one is allowed to gather such data, but it's pretty obvious that the corruption at higher levels approaches 100%.
That assertion rests on the assumption that the Chinese government is like a mafia family. That premise requires evidence. As I mentioned in another reply to you, I disagree with this premise and I gave my reasons why.
I even question the assertion that no one is allowed to gather data about the government's conduct or performance. The research "Sources of Authoritarian Responsiveness: A Field Experiment in China" [1] did exactly this.