<h3>Source</h3> <ul> <li>United Nations (2002), <i>Seventh Survey on Crime Trends and the Operations of Criminal Justice Systems (1998-2000)</i>, UN Office on Drugs and Crime, <i><a target="NEW" href="http://www.unodc.org/unodc/crime_cicp_surveys.html">www.unodc.org/unodc/crime_cicp_surveys.html</a></i>.</li></ul> <h3>Further information</h3> <h4>Analytical publications</h4> <ul> <li>OECD (2003), <i><a target="NEW" href="http://www.sourceoecd.org/9264197974">Society at a Glance: OECD Social Indicators, 2002 Edition</a></i>, OECD, Paris.</li> <li>Walmsley, R. (2003), "Global Incarceration and Prison Trends", <i><a target="NEW" href="http://www.unodc.org/pdf/crime/forum/forum3_art3.pdf">Forum on Crime and Society</a></i>, UNODC, Vienna, Vol. 3.</li></ul> <h4>Web sites</h4> <ul> <li>OECD Social and Welfare Statistics, <i><a target="NEW" href="http://www.oecd.org/statistics/social">www.oecd.org/statistics/social</a></i>.</li></ul>

<h2>Long-term trends</h2> <p>Since the 1970s, OECD countries have experienced steady increases in prison population, with the exception of Finland where the rate has continued to decline. Over the last ten years, Portugal has recorded one of the largest increases together with Spain among European countries. However levels in both countries remain far below the United States where the prison population has witnessed a huge jump that bears no historical comparison, with a population in 2000 four times as high as in the early 1970s. Differences across countries have, surprisingly, only little to do with the prevalence and development of crimes but more likely to do with political factors and responses to the increasing belief in certain countries that prison is preferable to other alternatives.</p> <p>When comparing prison populations in 2000, the United States again stands far above the norm with an incarceration rate five times as high as the OECD average and three times larger than the Czech Republic, ranking second. More than 1.2 million convicted American adults are in gaol (a little less than 2 million when pre-trial and non-guilty offenders are included), and this may have a significant distorting role on the labour market for young males. Rising prison populations, unless fully resourced, generally reduce the effectiveness of criminal re-education. Upward trends can pull down the staff-prisoner ratio, a key component for achieving effective prevention of re-offending and promoting reintegration in the community. Moreover, prison overcrowding tends to exacerbate already high levels of tensions and violence, raising the risks of self-injury, suicide and sexually transmitted diseases including HIV/AIDS. Overcrowded prisons are also more likely to act as "universities of crime"</p>

<h2>Definition</h2> <p>Not everyone in prison has been found guilty of a crime, especially those awaiting trial or adjudication. The indicator here considers only those sentenced to incarceration, excluding pre-trial and non-guilty offenders. The numbers of prisoners are shown per 100 000 population.</p>

<h2>Comparability</h2> <p>The data are collected for a typical day that can be considered representative of the whole year. This information is collected by the United Nations as part of its work on the operation of criminal justice systems.</p>

<p>Crime causes great suffering to victims and their families, but the costs associated with imprisonment can also be considerable. These costs are normally justified by reference to a combination of three societal "needs": to inflict retribution; to deter others from behaving in a similar way; and to prevent re-offending.</p>