Every part of your presentation should move your audience toward the goal that you set for the entire presentation. Simply dumping a data set into a graph in PowerPoint only gives your audience part of the story — just the raw information.
You are the expert. Ideally they want to know what you think, what you have discovered about the subject and how you see things. Give your charts and graphs a point of view by emphasizing the specific data that is critical to their understanding of your big idea or goal. Pull out the important numbers, enhance their display and show how those numbers are so important to the overall understanding of the content. Then add a headline and a sub headline that focuses their attention and you have a powerful graph that both shows the data and delivers your point of view.