According to the United Nations High Commissioner for Refugees, the number of people internally displaced within their own countries (also called IDPs) has reached a historical high of more than 28 million (see also here for the full report). The numbers of IDPs usually fluctuate a lot and go up and down as a result of the outbreak or settling down of internal conflicts within states. The current increase follows recent events in Sri Lanka and Pakistan. The countries with the largest numbers are Colombia (3 million), Iraq (2,5 million) and Sudan (2 million). (There’s an older map here).
More statistics are here.