According to Wikipedia, Iceland hasn’t reported literacy statistics to UNESCO.
Quite a few very high income countries have stopped tracking adult illiteracy.
Periodically, I form a scale of intelligence for the countries of the world from three underlying measurement:
[a] adult illiteracy [good for distinguishing among countries at the bottom],
[b] scores on internationally-standardized exams [good for distinguishing among countries from the middle to the top], and
[c] number of Nobel Prize winners in the sciences [good for distinguishing among countries at the top].
I include Nobel Prize winners because, in a free society, we should be anxious for the development of all of us. This includes a basic education for all. A large and prosperous middle class. And also the opportunity for the most gifted among us - whether in science, artistic expression, in leadership, wisdom or compassion - to bless us with the talent God has given them. In a free society, we do not need to level everyone to “the average.” We accept that God has made us each uniquely whom we are, that there is dignity in each of us, and that our good works, whether large or small, are acceptable because we are sanctified by the God’s grace.