The two graphs show the main sources of energy in the USA in 1980 and 1990 Write a report for a university lecturer describing the changes which occurred

the two pie charts illustrate 5 fuel sources of energy consumed in the USA from 1980 to 1990
Overall, it is clear that oil was the primary source of energy throughout the period. Besides, there was relatively little changes in the proportion of the others fuel source of energy throughout the period
In 1980, the amount of oil produced made up 42% of the chart, but this then fell to 33% in 1990. By contrast , the figures for hydroelectric power remained unchanged, at 5% over the period shown.Additionally 22% of energy generated in the USA came from coal, however there was a sharp decrease to 27% in1990
Turning to other features of the chart, the figures for natural gas witnessed a gradual decline from 26% in 1980 to 25% in 1990. In 1980, the figures for coal accounted for 5% , then this saw an increase to 10 % at the end of the period