The given graph illustrates the 
production
 Use synonyms
levels
 of the main kinds of fuel in the UK from 1981 to 2000. Units are measured in energy from one million tonnes of oil that produces Coal, Natural Gas, and Use synonyms
Petroleum
.
Use synonyms
Overall
, it can be seen that Linking Words
Petroleum
 had the highest Use synonyms
production
 Use synonyms
levels
 over the given period. Use synonyms
In contrast
, Coal and Natural Gas never reached more than approximately 110 energy units.
In the first Linking Words
year
, Natural Gas became the lowest Use synonyms
production
 Use synonyms
Use synonyms
levels
 Fix the agreement mistake
level
that 
stood at just below 40 and remained steady until 1990. Correct pronoun usage
apply
This
 kind of Linking Words
fuels
 Fix the agreement mistake
fuel
then
 experienced a significant Linking Words
rose
 in 1996 from just above 40 to approximately 80 before it reached a peak at just above 100 in the final Replace the word
rise
year
. Use synonyms
To
 the contrary, Coal Change preposition
On
that
 stood at exactly 80 in the first Correct pronoun usage
which
year
, significantly dropped to just below 40 in 1985. But, it Use synonyms
then
 witnessed a slight Linking Words
rose
 to approximately 60 in the next Replace the word
rise
year
 and remained steady until 1989. Coal Use synonyms
then
 slightly Linking Words
drop
 to just below 40 in 1994 and experienced a slight Wrong verb form
dropped
rose
 to exactly 40 in the next Replace the word
rise
year
 before it Use synonyms
keeps
 dropping until 2000.
Wrong verb form
kept
Petroleum
, as the highest Use synonyms
production
 Use synonyms
Use synonyms
levels
 over the period, stood at just below 100 and Fix the agreement mistake
level
wittnessed
 a Correct your spelling
witnessed
significat
 rose Correct your spelling
significant
at
 approximately 140 in 1984. But, in 1990, Change preposition
to
Petroleum
 significantly Use synonyms
drop
 to exactly 100 before it reached a peak at just above 140 in 1999.Wrong verb form
dropped