According to this website, the population of Ethiopia is projected to nearly double its current size by the year 2050, making Ethiopia the 10th most populous country in the world.
Ethiopia's current population is about 77 million according to the Central Statistical Agency of Ethiopia (click on the figure below for details). This means Ethiopia's population has more than tripled in the last 40 years.
I am not sure what the current population growth rate for Ethiopia is. Whatever it is, it is way too high. With the way things are going in Ethiopia (politically/ economically/ socially), one does not have to be a rocket scientist to predict that the country will be in far worse predicament (politically/ economically/ socially) in the year 2050 with a population size that is double its current size. This population explosion is the number one problem that is facing Ethiopia today bar none.