That is a difficult question to answer accurately. It is my belief that caps were maybe 20% of the headgear. By the way, in nearly all contemporary accounts, I have found them referred to simply as caps, not kepis. I cannot base this on anything resembling any scientific research, just my impression and opinion. In most letters and diary accounts that I have seen, hats are mentioned from time to time while caps were seldom mentioned. Also, the few 1864 AOT clothing reciepts that I have seen mention hats, but not caps. As to the various clothing depot records, I have not had access to any of them. Caps are much easier to manufacture than hats. I have seen some quartermaster records of units from the Texas coast and was surprised to see that caps were made and regularly issued from the Houston, Texas Depot up until the very end of the war. These were equipped with leather brims and not painted cloth. Also suprising to me was that those issued to artillery units along the Texas coast were of the regulation red color. I know that your question was concerning AOT units, but I thought this Trans-Mississippi information would be interesting to the subject. It is generally thought that for field use, the hat was preferred over the cap and in my reenacting experience, I also feel this way. Not really much difference in the winter time, but a hat is much better protection in the spring and summer. Another tidbit of info - the Yankees burned a hatmaking factory at Northport, just across the river from Tuscaloosa in April 1865. The hat that Gen. Lee wore at Appomattox and is now in the Museum of the Confederacy at Richmond, was made at this factory.