If you mean from this list of options:
a. The numbers of refugees from southern Europe decreased, while the numbers from Africa increased.
b. The numbers of refugees from Asia decreased, while the numbers from southern Europe increased.
c. The numbers of refugees from southern Europe and Africa both increased.
d. The numbers of refugees from southern Europe and Africa both decreased, while the numbers from Asia increased
Then the correct answer would be a - the number of people from Europe decreased, while the number of people from Africa increased. The reason for this is simple - Europe had become more stable during this time, while different portions of Africa suffered alot of civil war and instability.