I've been on the "How Many Left" website a few times looking at various bits of data, not least how many of my Mk2 16vs there are still knocking about.
However, it was interesting to see that only 1184 Golf GTis were registered in 2009 (the year of the Mk6 coming out which will no doubt include some Mk5s too), 1120 in 2010, 864 in 2011 and only 494 in 2012 (although I think that's only the first half of 2012 at the moment). Not as many as I would have thought.
What was most interesting was that precisely 1 Golf GTi cabriolet was registered in the first half of 2012. I confidently predict a big fat zero for the R cabriolet.
Anyway, have a gander on the website if you're a geeky number type like me.