The graph is misleading because it appears to be showing a huge increase, however, it is showing this increase over a huge time span of 13 years, which is actually quite a small amount for only a few hundred customer increase.
It is misleading Because the points on the X-axis are not all in the same unit. If you look at the x- axis, you will see it goes from 1991 to 1997. The years should be numbered the same units apart.