Study on gas permeability of batious kinds of cork

[The Kitten King]

I don't know if this is the best source or not, but it's the only thing I could find measuring the level of oxygenation using various types of cork. Its for wine not shine, but i dont see why it wouldnt be applicable. The tl;dr is that synthetic corks are way more permeable.

http://www.portocork.com/docs/bordeaux_study_002.pdf