From the report:
Included in the case-by-case records obtained by TRAC is information about what the Justice Department calls the "lead charge" and the sentence that was imposed. The data show that the majority of defendants received no prison time other than time served while waiting for their cases to be resolved (see Table 2). During the first three months of FY 2013, nearly three out of four prosecutions (73 percent) were for illegal entry, a petty offense under Title 8 Section 1325 of the United States Code. In second place were prosecutions for illegal re-entry, a more serious felony charge. A total of 20 percent were re-entry prosecutions. For those convicted on the basis of the second charge the median prison sentence was 6 months.
Click here to read the rest of the report.