The pie charts give information about the changes in five sources of energy (oil, natural gas, coal, hydroelectric power, and nuclear power) for the USA in the years 1980 and 1990.
Overall, the USA used oil as a main source in both years, while hydroelectric power produced the least energy. The energy produced from oil and natural gas showed a downward trend, whereas an increase can be seen in the figures for coal and nuclear power.
The amount of energy produced by oil was 42% in 1980, then the proportion decreased to 33% in 1990. Hydroelectric power, which was the lowest energy source, produced 5% of energy and remained unchanged during the period given.
There was a decrease in the two biggest proportions, oil and natural gas, in 1980 and 1990. The energy produced from oil slightly declined by 9% in 1990, while natural gas went down by just 1%. In contrast, the figures showed an incline in coal at 27% and nuclear power by half at 10%.