In Finland its around that percentage at 7 years old! But there's a very recent trend (as in I've only starting hearing about it on the news this year) of parents opting for watch phones for first phones instead of going straight to smart phone once their child starts school.
My DD is in 13 now and this year in school they are told to use their phones in PE for example, using fitness trackers to track them when they go for a 5k walk/jog round town, and take selfies at certain landmarks to prove they went there, so they need to have smart phones with internet access. They also get to use them to listen to music with headphones in art, if it helps them focus. But other lessons they get taken at the start of the lesson and returned at the end.
Homework thankfully is not screen based the vast majority of the time, its mostly done with their textbooks and workbooks. And screens are used rarely in class, again its mostly actual physical textbooks (I was worried they would have switched to digital textbooks when my DD started at upper school this year but they haven't yet)