The Pew Research Center has performed studies on international religious freedom between 2009 and 2015, compiling global data from 16 governmental and non-governmental organizations–including the United Nations, the United States State Department, and Human Rights Watch–and representing over 99.5 percent of the world's population. In 2009, nearly 70 percent of the world's population lived in countries classified as having heavy restrictions on freedom of religion. This concerns restrictions on religion originating from government prohibitions on free speech and religious expression as well as social hostilities undertaken by private individuals, organisations and social groups. Social hostilities were classified by the level of communal violence and religion-related terrorism.