Complex sentence: More than two-thirds of the population (74 million people) is under the age of 30 while net enrollment at primary school level is almost 100%, preluding a secondary "demographic boom" in Iran in the coming years.
Split into simpler sentences: More than two-thirds of the population (74 million people) is under the age of 30. Net enrollment at primary school level is almost 100%, suggesting a secondary "demographic boom" in Iran in the coming years.