I'd wager 20% of Norway or more has been actively following these games. Everyone has been talking about it, the last few weeks the lunch at work has been mostly discussing the game the night before. All over the media. Biggest tv channel (NRK) showed the 15 games live, same for the biggest news page (VG) .
And this is nothing new, ever since the first time Carlsen was in a WC match Norway has been obsessed with chess. Some joke it's because we're so fond of slow-tv here. Both NRK and VG has made it like a panel/talk-show with a mix of chess experts and entertainers. The format works well.