The 'overview' is a really important part of your task 1 essay. It's a summary of the main things that you can see on the graph or chart, and I suggest that you write two sentences describing two main things that you notice.
What two main things would you choose for the graph below?
The graph below shows the average number of UK commuters travelling each day by car, bus or train between 1970 and 2030.
Tip: Don't look for particular years or numbers. Look at the overall trend over the whole 60-year period.