In fact (if possible - it may not be) it'd be good to see it by major urban area, because that might show things quite well. Even in Yorkshire I get the impression that it varies quite a bit.
The other thing is that if you look at say the U12 and under lists, they look overwhemingly southern to casual inspection. Then much less so as you go further up, and far less so (if at all?) at adult level. It would be interesting to try and work out why. People keep playing for a very long time of course but if this has been going on for a bit you'd have expected it to have filtered through by now.
(3C's for instance are very obviously obviously dominant in Manchester.).
Finally of course, listen to Phil not me or the stats. Much more reliable