# How does dichlordifluormethan get into the stratosphere?

I was currently wondering why FCKWs are able to destroy the ozone layer. It looks for me like these gases have a high molecular weight in comparison to $\ce{N2}$ or $\ce{O2}$. How can these gasses come up to the outer layer of our atmosphere? In detail, how long (averaged) the diffusion of such an particle would take to get to such a altitude?

I mean, they are basically several times heavier than all the other components of our atmosphere and it shouldn't be energetically very stable for them to float on the outer layers to space on the top of lighter particles.