On the heels of 2013's Yeti, Turn Out the Light! and 2014's Spaghetti with the Yeti and The Really Abominable Snowman, we saw published this year:
The Thing About Yetis by Vin Vogel
here and here.
And The Snow Beast by Chris Judge
That's six picture books out in 2015.
And that's not even including the heavily illustrated kids books Pugs of the Frozen North and the Yeti Files 2, nor the kid-friendly comics Lumberjanes and Abigail and the Snowman.