USAF (and USAAF) Statistics

Army Air Forces Statistical Digest - World War II (Second Printing) (December 1945) (17.2 MB PDF)
Army Air Forces Statistical Digest - Supplement Number 1: 1945 (April 1946) (4.7 MB PDF)
Army Air Forces Statistical Digest - 1946: First Annual Number (June 1947) (13.9 MB PDF)

More supplements for the period 1945 to 2009 can be found at the U.S. Air Force's Historical Studies Office. (LINK)