In all, there were 28.2 million people internally displaced worldwide in 2012. This is a record high since the organization began collecting these statistics, and is a 2.4 million person increase over last year. This is largely because of the Syria conflict.
IDPs are generally more vulnerable than international refugees, because at least refugees are covered by various international legal conventions. IDPs are often not covered and not granted the same kinds of protection or special status. There are actually about 2 IDPs for every refugee in the world.
One data point that sticks out from this map: Colombia is the country with the largest population of IDPs, with estimates from the government and civil society ranging from 4.9-5.5 million. That shows how uprooting a protracted, decades long civil conflict can become.