If we go back to the industrial period, countries are developing rapidly and were in great need of labor, so the required population genes were in high demand. The number of people giving birth to children was not high either, and it was easier to shave off the children than it is now. On the contrary, looking at the current situation, the concept of young people lying flat is getting stronger and stronger, and the aging of the population is getting more and more serious. In the past, the average fertility rate was above 3-4, which represented an increase in population. The current trend is that the population is aging, the younger generation is getting married later, and many of them choose not to have children. Even if they are born, only 1-2. The fertility rate in many transitions now s