The 13.6% likely includes people like Vera Braz, Hugo Martins de Carvalho, or Paulo Ramalho who have essentially light but somewhat greenish or mixed eyes. Damiăo de Góis findings and my own for pure light depart over only a few such individuals with light mixed eyes. Blue and light greyish with no apparent mixture would be slightly less.
Vera Braz for example, do you consider this pure light like Damiăo de Góis does or light mixed like I do?:
https://i.ibb.co/Kbn7DL0/Braz.png
I got 7-8% for blue-grey without any admixture just like Tamagnini regardless of uncertain cases.
It appears your standards for pure light are slightly more lenient than my own: