Let's try a different tack then - if it's illegal to disapprove of the government and you'll be locked up for it, and 10% of the population voice disapproval, why are only 0.12% of the population imprisoned? Do you actually understand the logistical undertaking disappearing or imprisoning over 140 million people would be? Do you not think it's more likely that it's just not illegal to disapprove, and that they really do generally approve of their government?
The 90% figure comes from the Harvard Kennedy School ASH Centre for Democratic Governance and Innovation. There is no fucking possible way you are suggesting that Harvard University is distributing CPC propaganda.