The two pie charts compare the production of energy from different five sources in the USA in 1980 and 1990

Overall, oil was the primary source of energy production, while Hydroelectric power produced the least power. However, natural gas accounted for one-fourth of the energy generation. The energy generation from both Coal and Nuclear power increased over the period.
In 1980, oil was the major source that produced 42% of electricity. However, although production from oil decreased slightly to 33% in 1990, it was the dominant source. In contrast, Hydroelectric contributed least as it produced only 5% of the total production. Natural gas was the second most used source for energy generation, producing a quarter of the power in both the given years.
On the other hand, both coal and Nuclear power generated 22% and 5% power in 1980, which increased by 5% for both in 1990 and with this rise, nuclear power had become the second most used source in 1990.