The given line graph compares two types of domestic heating fuel used by households built in four periods.
The overall data shows that the use of electricity gradually became popular through the decades, while people who chose the nature gas showed an downward trend and finally reached the same figure with the percentage of eletricity in 1990-2010.
We can see that the figure for households choosing electricity for heating fuel had a consistent increase over the period. Only 15% of houses constructed before 1950 used electricity, whereas in the next ten years, the percentage rose to 25%. By 1990-2010, the figure had steadily went up tp 45%, reaching to its peak through out the decades.
By contrast, the use of nature gas followed an opposite pattern over the years. Before 1969, there was 60% of homes chose nature gas for heating fuel, whilst the percentage of those built in 1970-1989 fell to 45%, remaining the same level in 1990 to 2010.