The given line graph illustrates the production of the main fuels in the United Kingdom over the course of 19 years, from 1981 till 2000.
Overall, it is evident that at the start of the period Petroleum was the most produced fuel, while natural gas was the least. However, by 2000 petroleum maintained its dominant position, while coal appeared to be the least produced type of fuel. Additionally, natural gas was the only fuel which had shown an increasing tendency in terms of energy units throughout the whole period.
To begin with, at the start of the period petroleum was produced at about 90 energy units, then, in the next 5 years it has experienced an upward tendency in terms of its production reaching 140 energy units in 1986. However, in the following years the production level started to decrease and in 1991 it dropped to 100 energy units. However, from that time and on, the production rate of petroleum began to increase, and in the last year it amounted for 140 energy units. When it comes to coal, in 1981 the amount of energy units that are required to produce this fuel accounted for 80, the the numbers started to decline and in 1984 it was a bit less than 40. In the next three years production level of coal had increased and reached about 60 energy units. However, in the following years number started to decrease again and in the last year it amounted for about 30 energy units.
Regarding natural gas, it was the only category which had experienced only ceiling trend throughout the whole period. In 1981, the production rate of natural gas was a bit less than 40 energy units and till 1990 it remained unchanged. But, in the rest of the period there was only an increasing tendency in production of natural gas and in 2000 this number accounted for slightly more than 100 energy units.