On average across the OECD in 2018, 21% of teachers work in schools with more than 10% of students whose native language is different from the language of instruction …

„On average across the OECD in 2018, 21% of teachers work in schools with more than 10% of students whose native language is different from the language of instruction, according to principals, and 18% of teachers report having more than 10% of students whose first language is different from the language(s) of instruction in their target class.“
OECD (Hrsg.), „TALIS 2018 Results. Volume I“ (2019), S. 83
In Österreich sind es 51 % bzw. 42 %.