I've seen a few cocks in my time and in my experience Australian guys my age (30) are about 50/50; older guys are more likely to be cut and younger ones more likely to be uncut. A few other relevant factors seem to be religion (obviously), city/country (circumcision is a traditional thing so it seems to have lasted longer in the country), race and probably even an element of class. My parents are fairly libertarian (didn't have us baptised either, they left it for us to decide our religious views). Also, I once went out with the son of a surgeon and he was uncut, which is not surprising since that is the position of the AMA.
Can't really explain why but I find the whole who is and who isn't question fascinating.