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

The pie charts compare the percentage of five fuel sources used to produce in the USA in 1980 and 1990.
Overall, it is clear that in both years, oil which was the primary source used for energy production, had the greatest change in the proportion. Besides, there was a realatively change in the percentage of other fuel sources in the years 1980 and 1990.
In 1980, 42% of energy produced in the USA came from oil, while there was a gradual decrease of using oil with 33%.The figures for natural gas, the total energy production remained almost stable at 26% in 1980 and 25% in 1990. However, the rise change was seen in both years with 22% and 27% for coal energy. Besides, there was a double rise in the proportion of nuclear power used to produce energy from 5% in 1980 to 10% in 1990, while the hydroelectric power remained at 5% of the total energy production in both years.