Yes, but I missed the legend the first time. They place it well above the pretty picture. It's an interactive chart, it turns out -- individual data points can be identified by clicking on a point. Edit: I checked again. The original chart has a grid. The x-axis is the year the film was released. (They also color-code the points by decade.). The y-axis is how much money it made. Neither set of indexes is visible on this Reddit page, and neither are the grid lines.