I saw this article on www.marketwatch.com and thought it might interest currency collectors: "...The U.S. Government printed 3 billion $100 bills in the 12 months ended Oct. 31, according to a Tuesday note from Nicholas Colas, ConvergEx Group chief market strategist. That’s 100% more than the average production of $100 bills over the past 5 years, and 50% more C-notes than $1 bills printed in the same period, according to Colas. Hard cash holds a special place in global finance as the preferred mechanism for drug, illegal arms and tax evasion transactions, Colas notes, and $100 bills are the preferred denomination. While the use of smaller denomination bills has fallen in recent years with increased use of credit and debit cards, demand for $100 bills appears to be growing. Part of the sharp increase in the number of $100 bills may be because of delayed production of a newer version of the note, which has had technical problems. So a lot of the newly printed bills may not yet be in circulation. And, per the Bureau of Printing and Engraving, “Over 90 percent of the notes that the BEP delivers each year are used to replace notes already in, or taken out of circulation..." [more]
I'm thinking the large volumn has to do with the issues they have been having printing the new design.