The line chart below shows the number of three main fuels generated by a European country over the period of 19 years starting from 1981.
It is clear that there was a remarkable rise in the production levels of petroleum and natural gas, while coal caught the eye with a dramatic collapse during the period.
In 1981, 100 tonnes of Petroleum were produced, which was higher than 20 tonnes compared with Coal at the same time. Not stopping at these numbers, the number of petroleum continuously expanded to more or less 130 tonnes and remained the statistic until 1986. On the contrary, the stage from 1984 to 1986 witnessed up and down of Coal from 80 to 42, 70 tonnes. Starting in 1986, the production proportions of both Petroleum and Coal immersed in a significant decrease.
Despite the continuous change of Petroleum and Coal, the quantity of Natural gas still stabilized at 40 tonnes for 14 years starting in 1981. The stage from 1995 to 2000 showed a rocketed trend in the number of production levels of Natural gas with over 80 tonnes. While an initial strong development of Natural has, Coal continuously downed up to 50 tonnes along with the quantity of Natural gas in 1967. Petroleum still took the top position of quality of all fuels during the remaining period.