John's graph was enough to convey the point, but I agree this one is an improvement. I don't know that I've seen this exact plot style before, but it's exactly

John's graph was enough to convey the point, but I agree this one is an improvement. I don't know that I've seen this exact plot style before, but it's exactly what came to mind for me after reading the intro of this article. It's the "stem plot" version of a side-by-side bar chart.