The supplied graph illustrates the production levels of the main types of fuel in the United Kingdom from 1981 to 2000.
Looking from an overall perspective, it is readily apparent that there are a total of 3 main lines representing three types of fuel with comparison to energy units: coal, natural gas, and petroleum. The petroleum line has the highest rate in energy units, whereas the coal trend is the lowest one.
As presented in the illustration, initially, the coal line started with 80 energy units, but shortly, in 1983, within a period of 5 years, its line rapidly decreased. Soon, the coal line rose up a little, to the point of 60. Then, its line had a slowly decreasing trend. While the petroleum line graph had an explosion in 1981 and reached a maximum in 1983 with 140 energy units, and until 1986, it kept this rate. After that moment, the line began to slowly decrease but stopped in the year 1990. Then, it started to grow up again until 2000, reaching 140 energy units. In contrast to all the graphs, natural gas was the most predictable. It started with 40 energy units and began to grow slowly, without any stops and pauses, and this line ended with a number of 100 in the energy units rate.