The Last Christmas

In the far, far north grows a lonely tree. Legend has it that when this tree is cut down, there will never be another Christmas. Ten years ago, a woodcutter drove a marker into the trunk of the fifty-foot tree at a point half his own height.

Not knowing of the legend, he promised himself he would finally get around to felling this lonely tree when the marker was as high as he. This woodsman was a bit of a legend himself- he was twenty-five feet tall ten years ago (Legends are rife in the northern reaches where it's winter year round).

Ten years ago, the woodsman grew at a rate of a foot a year. Today he grows at only eleven inches per year. Every ten years (on the dot) his rate of growth shrinks by an inch. Someday, he will stop growing altogether.

The tree, on the other hand, will grow until it is cut down at a rate of one inch per year.

If legends live forever (and were true), in how many years will the last Christmas be?