The way we use energy resources has changed a lot over the last 150 years. Electricity use has increased as more homes, factories and devices have been connected, and a growing population needs more energy. Coal was the main fuel for electricity for many years. Oil and gas then grew in importance, with gas boosted by supplies found under the North Sea, and nuclear power began generating electricity in the 1950s.
In recent years coal use has fallen sharply in the UK. Burning coal releases a lot of carbon dioxide, which adds to global warming, so governments set targets to cut it. Wind and solar use has grown, helped by government targets and a falling cost of building them.
Renewable resources are not a complete answer yet. Wind and solar depend on the weather, so they are less reliable than fossil fuels. Other factors that affect which resource is chosen are cost, how much fuel is available, how quickly a power station can respond to demand, and the effect on the environment. Reading a graph, you should describe the trend (rising, falling or steady) and give a reason.