Well that particular chart was not designed to be anything but a snapshot of the last seven days updated every 4 hours. I will put into development pipeline. Making curation data from previous days would mean that I have to persist the data in JSON like I did for the massive curator history dataset. It is doable, but will probably have to be built as a going forward daily thing with a limit on data retention so that JSON doesn't grow too big.

You might be interested in a brand new dashboard that shows information on the top 100 curators for the past 5 years that I have just built and deployed today: https://seattlea.z5.web.core.windows.net/curator-voting-history-dashboard.html

It is kind of a beta version still...