<P> Comparing some countries with similar percentages of immigrants, Germany has an incarceration rate of 76 per 100,000 population (as of 2014), Italy is 85 per 100,000 (as of 2015), and Saudi Arabia is 161 per 100,000 (as of 2013). Comparing other countries with a zero tolerance policy for illegal drugs, the rate of Russia is 455 per 100,000 (as of 2015), Kazakhstan is 275 per 100,000 (as of 2015), Singapore is 220 per 100,000 (as of 2014), and Sweden is 60 per 100,000 (as of 2014). </P> <P> A 2014 report by the National Research Council identified two main causes of the increase in the United States' incarceration rate over the previous 40 years: longer prison sentences and increases in the likelihood of imprisonment . The same report found that longer prison sentences were the main driver of increasing incarceration rates since 1990 . </P> <P> Even though there are other countries that commit more inmates to prison annually, the fact that the United States keeps their prisoners longer causes the total rate to become higher . To give an example, the average burglary sentence in the United States is 16 months, compared to 5 months in Canada and 7 months in England . </P> <P> Looking at reasons for imprisonment will further clarify why the incarceration rate and length of sentences are so high . The practice of imposing longer prison sentences on repeat offenders is common in many countries but the three - strikes laws in the U.S. with mandatory 25 year imprisonment--implemented in many states in the 1990s--are statutes enacted by state governments in the United States which mandate state courts to impose harsher sentences on habitual offenders who are previously convicted of two prior serious criminal offenses and then commit a third . </P>

Percentage of us population that has been incarcerated