I was going to suggest the ability to edit the 'share date' when you edit a tank, so that you don't have to enter in a date when you put a tank in (as is now) but you would be able to properly date a tank that you entered with a bunch of other tanks so that the monthly type graph could be plotted, perhaps as an option or secondary graph?

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings