I don't think Phillips/Kendall publishes NOACK percentages but they typically test relatively high from what I've seen...so I'd guess it's probably at the higher end of the Dexos approval NOACK level, which I believe is still limited to 13 on the high end.
PQIA had a test from 2013 that had this weight of GT-1 at a 10.7 NOACK that you've probably seen but I would doubt that's still applicable. They had a 5w-20 synthetic blend version of this oil that was tested at a NOACK of 15.1 in 2014.