"On January 1, 2008 more than 1 in 100 adults in the United States were in prison or jail.[13][14]
In 2008 approximately one in every 31 adults (7.3 million) in the United States was behind bars, or being monitored (probation and parole). In 2008 the breakdown for adults under correctional control was as follows: one out of 18 men, one in 89 women, one in 11 African-Americans (9.2 percent), one in 27 Latinos (3.7 percent), and one in 45 Caucasians (2.2 percent). Crime rates have declined by about 25 percent from 1988-2008.[15] 70% of prisoners in the United States are non-whites.[16] In recent decades the U.S. has experienced a surge in its prison population, quadrupling since 1980, partially as a result of mandatory sentencing that came about during the "war on drugs." Violent crime and property crime have declined since the early 1990s.[17]"

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http://en.wikipedia.org/wiki/Incarceration_in_the_United_States