According to global data from 2018, Niger had a natural rate of increase equaling 3.8% and Bulgaria equaled -2.8%. What process was used to calculate this statistic?
O Averaging the fertility rate for the past 100 years
O Multiplying the crude birth rate by 10
O Subtracting the crude death rate from the crude birth rate
O Dividing the crude birth rate by the sex ratio
O Adding the death rate to the fertility rate and dividing by two
