More than 9.25 million people in the world are held in penal institutions, according to the 2007 edition of the World Prison Population List, produced by the International Centre for Prison Studies in London. This represents an increase of a quarter of a million since the previous study in 2005. Drawing mainly from official statistics from 214 independent countries and dependent territories, the report reveals that almost half of those imprisoned are in the U.S., China, and Russia. The data is weakened by regional differences such as whether juveniles, the mentally ill, or pre-trial persons are incarcerated and whether prisons are government-run or privately run. The list also states:
- 738: Number of prisoners per 100,000 people in the United States—the highest prison population rate in the world.
Source: "World Prison Population List (seventh edition)," by Roy Walmsley (International Centre for Prison Studies, King's College London).