These pie charts illustrate various fuels that could produce electricity in the USA over 20 years. 
Overall
, Linking Words
while
 most of the fossil fuels witnessed a downward trend except coal, the opposite could be seen in renewable Linking Words
energy
. Noticeably, hydropower was the less favourable choice. 
In traditional Use synonyms
energy
, accounting for 42%, the percentage of Use synonyms
energy
 generated by oil was the highest in 1983, followed by coal and natural gas with 23% and 11% respectively. Use synonyms
This
 figure decreased moderately by 3% for 2 decades which was the most used Linking Words
energy
 in 2003. Use synonyms
Similarly
, the growth from 11% to 21%, witnessed by natural gas, made it become the second most used traditional Linking Words
energy
. Use synonyms
In contrast
, a decrease of 10% was seen in coal from 1983 and 2003. 
Linking Words
On the other hand
, in 1983, among renewable Linking Words
energy
, Use synonyms
while
 hydropower only consisted of 4% of ways to generate electricity, which was the lowest, the other Linking Words
energy
, nuclear power, grew by 4% in the Use synonyms
last
 observed period. Strikingly, hydropower remained stable at 4% over 20 years.Linking Words