Compare the monthly retail sales, by dollar and by unit, of calendars.
 Alternatively (because I believe that such as Calendars.com, possibly
a division of Barnes & Noble, may consider that information
propriatary) provide any reasonable first-or-third-party commentary. 
It is because of this early "stopper" that I price THIS question so
low;  but I also invite your interest in my question regarding
pre-teen clothing sales, which must be available with sharper edges.