The line graph below shows the percentage (%) of houses in Anyland heated by systems using four sources of energy.

The line graph illustrates the proportion of people heated by systems using coal, gas, electricity, and solar in Anyland from 1950 to 2030. It can be seen from the line, there was an upward trend in the percentage of using electricity and solar, whereas coal and gas were consumed less than in the majority of the period. Another striking feature is that electrical energy has been becoming dominant than other sources. The statistic for using electrical energy rose sharply to 10 percent in the period of 20 years, starting in 1950, before soaring to 90 % in 1990. However, there was an oscillation of over 95% in the percentage of houses heated by using electricity for systems between 1990 and 2020, followed by a slight drop of approximately 90% in the last decade. Nevertheless, solar was the less consumption in four sources of energy, which bottomed out from 1950 to 1990, then that has been climbing to 10% in 2030. On the other hand, the figure for coal undergone a swift fall of under 10% in 1990, after increased slightly to 73% in 1960. While the proportion of people using gas as a source of energy for warming systems was 30% in 1950, followed by a minimal decrease of 20% then riched a plateau from 1960 to 1980. From that time, people used gas unusually, which declined to an insignificant amount. The most dramatic changes will be seen in 2030, the amount of coal and gas energy will be leveled off.