Given are the two charts regarding the primary sources of energy in the USA over a decade (from 1980 to 1990). The figure measured by percentage.
Overall, during the period, the most massive energy was produced by oil, while the least one was hydroelectric.
Looking at the details, we can see that the main source in the USA was oil, which was equal to 42% in 1980 and in the following decade it decreased by 9%.
At the beginning of the period, natural gas was about 26%, but at the end it slightly decreased to 25% respectively. There was a slight growth in coal 1990 by 5%. Comparing to the the beginning Nuclear power doubled in 1990, whereas hydroelectric power maintained the same level with 5%.