The given diagram illustrates the production of different types of fuels spanning over a period of twenty years in the United Kingdom. Predominantly, It is petroleum which has been produced more often than coal and natural gas.
Starting lower, natural gas was produced in minor quantities from just around 40 energy units per year in 1981, when in comparison to the other forms of fuels and skyrocketted its production towards the end of the 20th century. Conversely, the production of coal took a huge dip as the years went by. Its production went from being 80 energy units per year to close to half of its original production in the year 2000.
Petroleum was always in demand as the production for it never saw a huge dip. Its production was massive from being close to 90 energy units per year in 1981 to approaching over 140 energy units close to towards the end.
In conclusion, this graph comprehensively depicts the production levels of popular fuels used in the UK in the last two decades on the 20th century. It shows the use for coal has been declining over the years and the elevating adoption of natural gas. But most importantly it shows that Petroleum is the most popularly produced fuel in the UK.