Don't know but I suspect some very interesting stuff happens behind the scenes
a lot of hash came on line see below
Dec 17 2014 39,457,671,307 -1.37% 282,449,013 GH/s
Dec 02 2014 40,007,470,271 -0.73% 286,384,627 GH/s
Nov 18 2014 40,300,030,328 1.76% 288,478,854 GH/s
Nov 05 2014 39,603,666,252 10.05% 283,494,086 GH/s <<<<< but maybe this is where we are on the patterns of jumps
Oct 23 2014 35,985,640,265 2.81% 257,595,247 GH/s