"For the last four years, immigration cases have been the largest single type of federal offenses. This trend continued in fiscal year 2012, where immigration cases accounted for 32.2 percent of all federal cases, despite a decrease of 3,169 cases in the total number of immigration cases reported to the Commission. This decrease is the first since fiscal year 2006 and represents a 10.7 percent decrease in this type of case from the prior fiscal year. Even with this decrease, the number of immigration cases has increased by 97.0 percent over the past decade, and represents a much larger portion of the overall federal case load in fiscal year 2012.
"The number of drug cases has been relatively stable over the last five fiscal years. In fiscal year 2012, drug cases accounted for 30.2 percent of all cases. Firearms cases were 9.8 percent of the caseload in fiscal year 2012, a slight increase from the year before but less than the 10.9 percent of the caseload that these cases represented in fiscal year 2008. The proportion of fraud cases over that period also was relatively stable at 10.5 percent in fiscal year 2012, but has increased slightly from 9.8 percent in fiscal year 2008."

Source

US Sentencing Commission, "FY 2012 Overview of Federal Criminal Cases" (Washington, DC: USSC, July 2013), pp. 2-3.
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