Despite all the information you may have read, there is not one shred of supportable evidence that CFCs have found their way 40 miles up above the Earth. No one has ever found any up there because they are roughly five times heavier than air. They are like a brick in a swimming pool. It is not often that you will see a brick floating to the surface of your pool. CFCs are so dense that even as a gas you could fill a bucket with it and pour the contents of one bucket into another.
Not a shred of evidence except for thousands of measurements:
CFCs and other ozone depleting substances (ODS) are heavier than air. In a still room, they will pool on the floor. However, the atmosphere is anything but still. Numerous measurements have confirmed that these molecules are mixed nearly uniformly worldwide. In the same way that vinegar and oil normally separate when still, but mix when shaken, ozone depleting substances and air are thoroughly stirred together by winds in the troposphere.
Winds are also why the location of CFC and other ODS emissions is essentially irrelevant. CFCs released from a car in the U.S. are as likely to find their way to the stratosphere over India as are molecules released from much closer countries like China. Once they mix through the troposphere, CFC molecules eventually move into the stratosphere. Thousands of measurements over several decades have firmly proven the existence of these heavier-than-air molecules in the ozone layer.