[RayChuang88]

Much of the loss was caused by the enormous investment in robotic technology. Today, work places like automobile assembly lines and even underground coal mining require a LOT less people because computer-controlled machines are doing a lot of the repetitive or dangerous work that used to require a lot of laborers. (Indeed, you need a lot more technical knowledge in 2015 to work in a coal mine because of all those computerized mining machines.)

[Lurkina.n.Learnin]

Same thing in sawmills. They built new sawmills that dramatically increased production with way less people.