It doesn't currently because it's not very accurate. There is a big jump in BTC amount from about a year ago because that's when we launched the new version of the site. Since then we haven't had enough contributions of historical time series data, it's basically just me picking a couple of companies every now and then and improving the data set. 😁
But I'm planning to create a separate "charts" page and I think I can include it there with the appropriate disclaimers.