The line graph below depicts the manufacturing rates of three main fuels such as petroleum, coal and natural gas in a European nation spanning from 1981 to 2000.
Looking at the graph from an overall perspective, the petroleum and coal followed an erratic pattern over the period shown. Whereas the amount of natural gas tended to increase between 1981 and 2000. Generally speaking, the production of petroleum always headed the list of manufacturing levels.
According to the provided graph, the fraction of petroleum was approximately 100 tonnes since 1981. In 1983, it witnessed a gradual rise to 130 tonnes before remaining stable for 4 years. In 1988, the figure decreased moderately to just under 100 tonnes. Then, it hit a high of about 130 tonnes and experienced some fluctuations over a period 5 years (from 1995 to 2000).
With natural gas, it started at 40 tonnes in 1981 and stay unchanged over the following 13 years. There was a dramatic growth to 80 tonnes in 2000. In contrast, the proportion of coal stayed stable at 80 tonnes. Over 6 ongoing years, it reached 70 tonnes from a previous low of 50 tonnes. Having declined to 40 tonnes at the end of the period.