Final answer:
The peak of hydroelectric power usage occurred between 1970-1980.
Explanation:
In the context of hydroelectric power usage, the peak was reached between 1970-1980. During this period, hydroelectric power usage was at its highest before other sources began to surpass and lower its rank according to the data provided.
Learn more about energy consumption and hydroelectric power usage here:
https://brainly.com/question/39153506
