The chart shows the 
production
 levels of the main kinds of fuel in the UK during the period between 1981 and 2000. 
Use synonyms
Overall
, the UK produced petroleum Linking Words
in
 the highest Change preposition
at
level
. In the first ten years, the Use synonyms
production
 Use synonyms
level
 of coal was still higher than natural Use synonyms
gas
, except for 1984. But Use synonyms
then
 after 1991, natural Linking Words
gas
 Use synonyms
start
 to be produced more than coal, and the gap between those two Wrong verb form
started
production
 levels was getting wider and wider.
It is certain that petroleum was always the most popular fuel to produce in the UK between 1981 and 2000. Petroleum Use synonyms
production
's image fluctuates between 90 and 140 Use synonyms
energy
 Use synonyms
units
. It reached the highest point in 1999 with a number of about 143, Use synonyms
while
 Linking Words
that is
 90 Linking Words
energy
 Use synonyms
units
 for the lowest point in 1981.
Coal Use synonyms
production
, starting at the Use synonyms
level
 of 80 Use synonyms
energy
 Use synonyms
units
, Use synonyms
it 
first went flat, Correct pronoun usage
apply
then
 sharply decreased. After a year, it increased to the Linking Words
level
 of 60 Use synonyms
units
Use synonyms
,
 and slowly Remove the comma
apply
being 
produced less and less after 1989.
Beginning with less than 40, natural Unnecessary verb
apply
gas
 Use synonyms
production
 remained basically stable until 1990 when it slowly increased. In 2000, natural Use synonyms
gas
 Use synonyms
production
 arrived at the highest point, which is a few more than 100 Use synonyms
energy
 Use synonyms
units
.Use synonyms