My kid went to a bilingual school that taught English via immersion (the English teachers didn't even speak German). In grade 1 they learnt the alphabet both in German class and English, one letter a week.
I was amused that in English they learnt A, then B, and so on in alphabetic order. In German they learnt by frequency (according to this chart, "enirst"; I remember enrst so probably missed the "i"). I already knew "eatoni shrdlu" so this amused me more than it should have.
Looks very much web-based, and not cleaned properly. I conclude that because digits are pretty rare in a normal corpus, much rarer than x and y. The English list also has some punctuation included, and half of the Greek alphabet. The counting didn't exclude proper names and formulas, I suppose. So if you want to identify the domain of a Wikipedia page based on 1-grams, this is helpful; otherwise, less so.
I was amused that in English they learnt A, then B, and so on in alphabetic order. In German they learnt by frequency (according to this chart, "enirst"; I remember enrst so probably missed the "i"). I already knew "eatoni shrdlu" so this amused me more than it should have.