Varies, when new and even now for the most part, my '13 was/is pretty much 0-33% 1 blinking light, 33-66% one solid one blinking, and 66-100% two solid one blinking.
My '12 is quite different and lots of times I'll see SOC's much higher with less solid lights than my '13. My '12 is down 2 bars(my '13 has all bars) so I'm chalking it up to that, it also stops charging at ~90% SOC. It will be interesting to see what others have to say, especially for those with degraded batteries.
