The world's growing refugee crisis is not only about numbers. It is also about time. There are 17.2million refugees under UNHCR's mandate, and half of them are under the age of 18. By the end of 2016, some 11.6million refugees were in a state of "protracted displacement" - meaning that they were in situations where at least 25,000 people have been forcibly displaced for more than five years. For 4.1million refugees, exile has lasted for 20 years or more.