Births and deaths are natural causes of population change. The difference between the birth rate and the death rate of a country or place is called the natural increase. The natural increase is calculated by subtracting the death rate from the birth rate.
The rate of natural increase is given as a percentage, calculated by dividing the natural increase by 10. For example, if the birth rate is 14 per 1,000 population, and the death rate is 8 per 1000 population, then the natural increase = 14 - 8 = 6. That is 6/1000, which is equal to 0.6%.