In many cases a direct graph is not usable when it comes to a projection of more than one variable in a standard chart. This is when we need interactive graphs. These graphs work with a base object that in turn is mirrored against a different object with the same value. Now how does this work? Let's say that your presentation is about the population of a city in France; let's say Paris. But you want to shadow this object that is in this case Paris, to lets say a different big city in the Netherlands like Amsterdam. This is needed in your graph to show the difference in occupied space per capita. This calls for an interactive graphs layout.The first chart will picture object Paris while the second one will picture object Amsterdam. When looking at your chart we can see the Paris layout very clearly and when we move on to the comparison, the line of object Amsterdam will be shown. By using two variables to show this complicated explanation you will make this comparison as clear as day.
This will not only create a visible reverence point but also a clarification that will be much appreciated by the people attending your presentation. What you're doing here is taking two charts and making them into one very easily readable, and extremely explainable interactive graph. This will show your superiors at your corporate home office that you are very much on the ball and that the presentation that you have just shown is extremely well thought out, and that you posses the wisdom to think outside the standard graphs and charts box. So always keep in mind that for every chart needed there is the perfect one. Don't be afraid to try something new.