The example graphs confuse dependent and independent variables, putting quarters on the vertical axis. This makes the curve look negative, when in fact it's positive (up and to the right - usually a good thing). This really takes away from the example, as it takes seemingly important business data, and renders it in a negative way that I wouldn't expect or like. I strongly suggest correcting the example.
Otherwise this looks awesome.
P.S. Should this be a Show HN? It feels like one.