The graph shows the percentage of four different types of fuels in use between the years 1800 and 2000

The chart provides information regarding the changing in usage of several kinds of fuel over a 200-year period, from 1800 to 2000.

According to the graph, in 1800, the only type of fuel that people used was wood. Perhaps, at the time there was abundance of wood, so it was easy to get this fuel. A year after that, the new fuel, coal, was started to use by citizens. By 1900, while the demand for coal had increased substantially to nearly 70 percent, the demand for wood had fallen considerably to 35 percent. The decrease in wood was may be caused by many citizens changed their fuel to be coal, which was more practice.

A more detailed look in the second 100-year period showed that there were two new fuels which had good demand among society and these fuels resulted in decreasing of coal and wood demand. Oil and gas were introduced in the same year, 1900, but the demand for oil had been higher than gas for 100 years. On the other hand, coal usage decreased to the half of its percentage in 1900, 35 %. This proportion was same as the oil and gas proportion in 2000. Interestingly, there were less people and industry used wood and the demand for wood ended up in 2000.

To sum up, the demand for new type of fuel was higher until the next new fuels came and at the point, the old types of fuels started to decrease.