Populations tend to grow over time, meaning there are more workers. In order to maintain a constant level of worker productivity, the total amount of capital available to them must:
1. Increase at a rate at least equal to population growth.
2. Decrease slightly, as this will motivate employees to work harder.
3. Increase at a rate less than the rate of population growth.
4. Increase at a rate equal to the rate of inflation.
5. Stay constant over time, as inflation and population growth tend to cancel each other out.