The proportion of available workers in the game is only related to the age structure of the population (nothing else) (press the "6" key on the keyboard to view the age structure of the population). Generally speaking, workers are 25-50 years old.
The solutions are "immigration" and "changing health".
1, Immigration Bureau
Immigration is the best way to pursue only short-term effects. Most of the new immigrants are of working age, and the number of immigrants can be increased by "building new slums" and "demolishing the original houses in batches and resettling them".
2. Control the health level
The health degree of a city (health degree can be viewed by pressing the "7" key on the keyboard) directly affects the mortality rate of the population, and then affects the age proportion of the population. According to statistics, when the health level is "normal", the working population is the largest. The health level can be changed by changing the proportion of people who can enjoy clinics (areas without clinics can meet the requirements of housing upgrading by building hospitals).