A chart for supply efficiency throughout the game.
So the graph would show you when you were supply blocked of course (which is already nicely implemetend, GJ on that) but also curves showing supply available supply VS supply used at any point and some efficiency indexes, e.g. % of supply used at any point / as an average throughout the game. I notice that when I focus on not getting supply blocked for a couple of games, I tend to overmake supplies to be safe, which isn't all that efficient (I would like to see this inefficiency reflected). The ''time over 30% supply'' index in the training center is useful but I think it could be expanded into a graph with a bit more details.