Charging efficiency rating over time

Would be nice to see the charge efficiency rating over 5% increments from sat 10% to 100% as a means to fingerprint battery charging efficiency as soon as an owner links to TeslaFi, and then periodically run the same test each month, quarter, year etc. to see if battery charging efficiency is degrading over time. Currently I can only think of doing manual 5% charge intervals and colating the data in a spreadsheet. Not sure if this would require manual interval charging or if the existing days can be broken down automatically. Would make for an easy to use and qualify battery health meter. Would also potentially help owners identify the most efficient charging range for their batteries based in their driving habits/styles, as well as quantity how much money could be saved by only charging in the most efficient range. Could also help plan reduced cost of road this in areas that have high enough chargers density. Efficiency should be reflected in either or both cost and time relative to the incremented charge levels of the battery, not just per charge.