Jiro, even scientists today readily admit they do not fully understand the dynamics of the ozone development and they cannot conclusively say that there was no "hole" prior to 1974 when first discovered. Just like CO2's role in global warming. They also cannot prove that CFC is in fact causing (or has caused) the ozone to get thinner. This is the SAME TEMPLATE being used for the CO2 scare. "Ozone HOLE" sounds really scary to the uneducated saying it was solely caused by man's use of CFC just as using the words "global warming as caused by man's use of hydrocarbons to create additional CO2." Both of these instances never had any shred of proof that those things were the case. NONE!
Ask yourself. Why is there no ozone "hole" in the North Pole but the South Pole has it?
Ozone can only be created with the help of sunlight (UV rays). No sun. No ozone. Both poles get no sun 6 months out of the year. How come the North Pole does not have an ozone "hole" where must of the industrial countries reside that produced most of the CFC?
Secondly, there is no hole. Just a thinning ozone layer. No hole.
Look to the sun. That's most of the answer right there.