Seasonal factors.

they want to get as many cores done and out while the winter road is in place. ALso, moving the drills around gets more difficult when the ice is gone.

And if they mobilize 2 drills back from Big Sky next winter to explore other targets, then the rate also falls off.

Best bet is that this spring, Feb to May, they'll get about 50 done, and for the calendar year of 2008, maybe as many as 150. So the 5 years just gives them lots of flexibility to shift focus between their 5 or so family of exploration areas, and seasonal factors. In my view.