The data given depicts the production of 3 different fuels namely petroleum, coal, natural gas in the UK over a time period of 20 years from 1981 to 2001.
Initially, coal was around 130 million tonnes. In the next two years there was a gradual decrease, but there was steep decline and it attained a trough in the year 1984 which was below half of the initial value. Thereafter, it faced a major increase in the next 2 years and plateaued till 1988. The production started declining with another sharp fall in the year 1994 remained constant for three more years and once more substantially decreased to approximately 38 million tonnes finally.
In the beginning, petroleum and natural gas were quite less compared to coal at around 90 million tonnes and 70 b cm respectively. There was a gradual increase over the years and it peaked at around 110 b cm in the year 1990 and then faced a substantial decrease and a slight increase in the last 2 years, finally it was approximately the initial value in the latter. On the other hand, there were not much changes in the former. It is evident that, there are many fluctuations over the years reaching above 80 million tonnes in the year 2001.
Overall, there were drastic changes in coal and natural gas while petroleum had only few ups and downs. However, over the time period all of the values declined.