The line graph compares three types of fuels in terms of production extent in the UK over a-19-year period, starting from 1981.
From an overall perspective, it is readily apparent that both petroleum and natural gas witnessed an upward trend, except for coal. Additionally, petroleum possessed the position of most used type of fuel in all three mentioned.
In 1981, the figure for petroleum experienced a significant rise from just over 80 energy units up to approximately 140 in 1986, while coal, on the other hand, decreased to a half by 40, which initially was roughly 80 energy units. The natural gas remained unchanged at just barely 40 energy units before dethroning coal and becoming the runner-up in 1991, at just slightly over 50 energy units.
Also in 1991, petroleum figures dropped down for the first time, at about 100 energy units. Additionally, from 1991, the trend pattern for petroleum and coal diverged distinctively, while the petroleum had risen up again and had reached a peak at about 140 energy units, the figure for coal bottomed out and remained relatively stable at over 30 energy units by 2000.