These two pie charts depict the main five sources of power in two periods, 1980s and 1990s in the same country. It is clear from the graph that both oil and natural gas had the highest nation during these years.
According to what is shown, both oil and natural gas had decreased from 42%, 26% in 1980, to be 33%, and 25% in 1990 respectively.
As for coal, and nuclear power sectors, they were approximetly 22% and 5% in 1980s, afterwards rose to be at 27%, and 10% each. Furthermore, hydroelectric power remained at 5% all over those years.
To sum up, we could say that oil, natural gas, and coal were the biggest three sources in the USA, also they were fluctuating between 42%, 26%, and 22% at 1980, and 33%, 25% and 27% at 1990 respectively. As for nuclear power, it climbed from 5% to 10%. Finally, the hydroelectric power sector stayed at 5% during the decate.