What percentage of housing is in the hands of speculators who invested in real estate for its further resale?

For centuries, a person solves a problem in which, in place of an unknown number, there is a question of how to build a house in a short time, with the lowest costs and in good quality.

How to get a visa to China? How to do this as quickly as possible and at the same time not overpaying intermediaries and companies to tour operators.