I have a late 2013 rMBP. The battery recently hit its 1000 cycle milestone. It was at 80% health at that point, which is right in line with spec for that battery as I understand it. Now it's at 1095 cycles and it's at 64% health, with the battery status listed as "failing". Is this normal or no? I was expecting the battery to continue a linear progression so that, after another three years, the battery would be at 60% health, etc. Is that not how it works?