This last point is illustrated by the chart below, which compares the impact of doctors in different countries

This last point is illustrated by the chart below, which compares the impact of doctors in different countries. The y-axis shows the amount of ill health in the population, measured in Disability-Adjusted Life Years (aka “DALYs”) per 100,000 people, where one DALY equals one year of life lost due to ill health. The x-axis shows the number of doctors per 100,000 people. DALYs per 100,000 people versus doctors per 100,000 people. We used WHO data from 2004. Line is the best fitting hyperbola determined by non-linear least square regression. Full explanation in this paper.You can see that the curve goes nearly flat once you have more than 150 doctors per 100,000 people. After this point (which almost all developed countries meet), additional doctors only achieve a small impact on average. — https://80000hours.org/career-guide/how-much-difference-can-one-person-make/