You can tell what is going on here. The inset is mask wearing behavior. The main graph is self-explanatory. Now you could say that the low mask-wearing is because people haven’t seen much presence of CV-19. But Denmark and Sweden have had a lot of cases and deaths before, so I am not sure that holds much water. And Norway and Finland are experiencing the fall case surge. I think the lack of mask wearing is because they decided not to engage in mass(k) delusion like the rest of the world, and stick to the actual settled science.