The graph displays the usage of 4 different types of fuels between 2 years, from 1800 to 2000 in percentages.
Overall, at the start of the period, It was only wood that was used as fuel. And it became completely out of usage by 2000. People also started using coal after 1800, and it was mostly used fuel in 1900. There are other 2 types of fuel that started being used from the middle of the 200-year period.
In the beginning of the given period in the graph, only wood was available for people to use. Then it started declining continuously and in 1950, it was the least popular fuel compared to other three types of fuel. After 50 years, people stopped using wood as fuel.
People started using another type of fuel, coal after 1800. Coal consuption increased steadily untill the 1900s, and after that it started decreasing till the end of the period. Oil and gas were introduced in 1900. Interestingly, indicators of gas and oil increased steadily and reached their peak, which is the same as coal dipped (around 30 percent).