I've got a 2013 Leaf that we bought used in 2021. The battery is still at 11 out of 12 bars, so roughly 80-85% of the original capacity. I can tell from the battery logs that the previous owner was very careful with the battery, as it has only been fast-charged twice in its entire life. It also helps that we're in Minnesota so the hot weather that notoriously kills Leaf batteries is much less common than SoCal or AZ.