Final answer:
The population was growing at a rate of approximately 26.44% per year.
Step-by-step explanation:
To calculate the growth rate, we can use the formula:
Growth Rate = ((Final Population - Initial Population) / Initial Population) * 100
Applying this formula to the given data:
Population in 1990 = 643,000,000
Population in 2000 = 813,000,000
Growth Rate = ((813,000,000 - 643,000,000) / 643,000,000) * 100
Growth Rate = 26.44%
Therefore, the population was growing at a rate of approximately 26.44% per year.