That ionized band of atmosphere is so far up that solid data on what it's been up to, and even what it's up to now, are hard to come by. Three principles are certain. Ozone is created by the Sun's radiation striking the upper atmosphere. Very cold temperatures destroy ozone. Ozone isn't necessary to protect people from the Sun's radiation, where the Sun isn't shining.
Ozone is as seasonal as the leaves on the trees.
When the Sun flees south, the ozone goes with it. So far, Sun burn during the Arctic winter has proved to be one of our smaller problems. Seal skin bikinis haven't caught on with the Arctic dwellers. The shear magnitude of the drop takes the concern out of the report. We know that atmospheric conditions on the Earth's surface change greatly from year to year.