From the Introduction: "As part of its ongoing mission, the United States Sentencing Commission provides Congress, the judiciary, the executive branch, and the general public with data extracted from and based on sentencing documents submitted by courts to the Commission. Data is reported on an annual basis in the Commission's 'Annual Report and Sourcebook of Federal Sentencing Statistics'. The Commission also reports preliminary data for an on-going fiscal year in order to provide real-time analysis of sentencing practices in the federal courts. Since 2005, the Commission has published a series of quarterly reports that are similar in format and methodology to tables and figures produced in the 'Sourcebook of Federal Sentencing Statistics'. The quarterly reports contain cumulative data for the on-going fiscal year (i.e., data from the start of the fiscal year through the most current quarter). From time to time the Commission also reports data regarding other sentencing trends, such as resentencings or other modifications of sentences previously imposed."
U.S. Sentencing Commission: https://www.ussc.gov/