Best answer by woz
this has already been raised and it's work in progress. I and others have said the same.
Also gas and electric should have their own charts. (with their own scales)
If it's any help the statement does have a rolling annual estimate on it (rhs) but that too is a mystery, although OK as a very rough guide.
Perhaps write your meter readings on a piece of paper or enter on a spreadsheet until this is improved, tbh as the usage chart stands at the moment it's the best way.
PP must be the only supplier where to get your annual usage you have to dig through old emails to find monthly statements. And no, the tiny usage graph that has no units on the axis isn't any use