The 2014 edition (current to March 2013) added 64 pages over 2013. 400 to 464.
2015 will add 80-100 more pages?
What are they going to do at this rate? Split into volumes? Have a periodic all years set, with yearly book of just the previous year?
The problem is, if the book grows rapidly without bound, the price must increase rapidly too for the whole thing to be worth it to them to publish.