Number and quality of doctors in Sin

The statistics given by Amy Khor in Parliament has stirred many emotions among Singaporeans on the number of doctors and the quality of doctors in the island. I did not have the details on how the numbers and ration were arrived. We have now 1 doctor to 520 of the population. Is the population based on 3.3m citizens or 5.4m or should it include the medical tourists? Anyway how the data are