The presumption also reflects the "nature of the Guidelines-writing task that Congress set for the commission and the manner in which the Commission carried out that task." Just as the sentencing judge must implement the seven statutory factors, the Sentencing Commission must write guidelines that carry out those same objectives. The Commission wrote guidelines to carry out the statutory objectives, and it continues to do so, based on empirical evidence of over 10,000 sentences imposed in federal criminal cases. Sentencing judges will, in turn set forth their reasons for the particular sentence they imposed, whether within or outside of the Guidelines range. When the judge imposes a sentence within the Guidelines range, his or her balancing of the statutory factors coincides with the Commission's. That is the source of the presumption of reasonableness.