The given pie charts illustrate 
types
 of five main sources of Correct article usage
the types
energy
, namely, oil, natural gas, coal, hydroelectric and nuclear Use synonyms
power
, in the USA in 1980 and 1990.
Use synonyms
Overall
, what stands out from the charts is that Linking Words
while
 oil was the main source of Linking Words
energy
 in Use synonyms
both
 two years, that for hydroelectric Use synonyms
power
 ranked Use synonyms
last
.
With regard to the charts, the Linking Words
energy
 produced by oil experienced a significant decrease from 42% to 33%. Natural gas Use synonyms
was 
accounted for almost a quarter of the Unnecessary verb
apply
energy
 use in 1980 before experiencing a small decline to 25% Use synonyms
with 
ranking third in 1990. Hydroelectric Change preposition
apply
power
 remained Use synonyms
both
 the same and the least used Use synonyms
energy
 source in Use synonyms
both
 years with Use synonyms
at 
5%.
Focusing on Change preposition
apply
other
 two sources, Correct article usage
the other
both
 coal and nuclear Use synonyms
power
 use saw an increase. Use synonyms
While
 the former doubled from 5% to 10% in a decade, the latter rose from a little less than a quarter to 27%.Linking Words