Steps of constructing graph:
1. Mark the horizontal axis OX as Years and the vertical axis OY as Route Length (in thousand kilometres).
2. Along the horizontal axis OX, choose bars of uniform (equal) width, with a uniform gap between them.
3. Choose a suitable scale to determine the heights of the bars, according to the space available for the graph. Here, we choose 1 big division to represent 1000 Km.