"The vast majority of convicted defendants plead guilty. In fiscal year 2012, 97.0 percent of all offenders did so, the highest rate since fiscal year 2002.
"When offenders pleaded guilty, 45.9 percent received a sentence below the applicable sentencing guideline range, either at the request of the government, at their own request, or initiated by the court. Approximately 62 percent (62.4%) of these below range sentences were requested by the government, usually because the defendant had provided substantial assistance to the government or had agreed to have his or her case handled as part of an early disposition program.
"In the 3.0 percent of cases in which the offender did not plead guilty, 37.1 percent received a sentence below the guideline range. Only 6.1 percent of these below range sentences were requested by the government.
"Most federal offenders convicted of a felony or Class A misdemeanor received a sentence of incarceration. In fiscal year 2012, 7.1 percent of offenders received a sentence of probation (i.e., where no type of confinement was imposed), a rate that over time has decreased from a high of 14.8 percent in 1993. Another 2.9 percent were sentenced to periods of both probation and some type of confinement, and 2.8 percent were sentenced to a combination of imprisonment and community confinement, such as in a half-way house or through home confinement."

Source

US Sentencing Commission, "FY 2012 Overview of Federal Criminal Cases" (Washington, DC: USSC, July 2013), pp. 4-5
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http://www.ussc.gov/Research_…