Now you tell me that this means.
The graph shows Google Analytics data for December 23 to 25 (with the numbers deleted). Note that it gradually goes down as Christmas approaches and is at its lowest point on December 24.
Now look at the huge spike on Christmas day. Almost double the numbers of the day before. The only thing I can think of is that a lot of people got ereaders for Christmas and started Googling around to find out more about them.