The line graph illustrates the percentage of houses using different types of heating fuel according to the year of construction of the houses.
Before 1905, the number of houses that use electricity was around 15%, slowly rose to 25% between year 1950 and 1969. It continued to rise steadily and reached 45% after 21 years. This shows that the usage of electricity gradually increased when the home was built.
Conversely, before constructing the older homes in 1950 the percentage of natural gas was 60% and it was stablized till 1969. This figures declined to approximately 45% between 1970 and 1989. Moreover, the proportion also leveled off for the house built in 2010.
Overall, it is clear from the graph that the use of electricity in various homes saw an increase, while natural gas declined over the same period.
