The first international agreement for protecting the ozone layer was the Vienna Convention in 1987 which provided for discussion and monitoring. The Montreal Protocol of 1990 was signed by 51 nations and regulated CFC's and some halons. Developing countries had a 10 year grace period. Regulations could change as new data were incorporated The U.S. has not agreed to these strictures. Other molecules also react with ozone and are are increasing with time.
Carbon dioxide increases the levels of ozone via heating the atmosphere.
Methane also reduces the destruction of ozone by encouraging the formation of HCl. Nitrous oxide will increase ozone levels . None of these seem to be as important as CFC's. Climate Measuring - We have data for a little over 100 yrs. We need data for hundreds of thousands of years.