You can see a little bit of a slowdown there in the mid-'70s, but it matches up pretty well with the Second Industrial Revolution, when factories were learning how to electrify their operations.
大家可以看到在上世纪70年代中叶有一点停顿， 但这趋势与第二次工业革命的发展很像， 那时工厂都在学习如何让操作电气化。