Development of ozone depletion over the years

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 Chemical ozone depletion is not a quantity that can be measured

 directly.  Ozone is also influenced by atmospheric transport. The time

 at which the polar vortex breaks down varies from year to year.  One

 way to deduce the effect of chemical ozone depletion from the

 measurements is tto look at of the average ozone column in the polar

 vortex ("equivalent latitude" >63°). This quantity increases

 after the breakdown of the polar vortex (typically in March) due to

 the the transport of ozone-rich air masses towards the pole.

 Therefore the minimum of this quantity in March is an approximate measure

 of chemical ozone depletion in the Arctic. Here you can see this

 value for years up to and including 2019 and also the corresponding

 time series for Antarctica.