World War 2 occurred in the late 40's, so this is most likely why there is a dip in that age group.
China believes that building the Three Gorges Dam was an absolute necessity in terms of energy production because it can generate hydro-electric energy from Yangtze River. This hydro-electric-producing dam would generate less pollution than coal-fire generation and would slow the river from overflowing and destroying nearby villages.
Answer: Hydroelectricity.
Explanation:
So major areas is Spain, Italy, England, France, and also Germany.
More innovations caused the economy to flourish and for many more factories to be built.
