That fact that you can doesn’t mean that you should! I will say it once again.That fact that you can doesn’t mean that you should! Look at this slopegraph that was featured by “Information is Beautiful”
What does it say? What do the slopes mean? It’s a slopegraph, its slopes should have a meaning. Sure, you can draw a line between one point to another but can you see the problem here? In this nonsense graph, the viewer is invited to look at slopes of lines that connect dollars with years. The proverbial “apples and oranges” are not even close to the nonsense degree of this graph. Not even close.
This page attributes this graph to National Geographic, which makes me even sadder.
Boris Gorelik 