well, I have been reading this and musing on it....and I find I'm mot so worried about relative numbers of any particular areas....the truth is, folkish music is not a major force in most of the areas we have heard from.
    I think we need the cross-fertilization that sites like Mudcat can help provide. We on the East Coast of the US have met a LOT of people, especially from the UK, but also from Canada and some other amazing places! in recent years due to the FSGW Getaway, and I know that some of us have gone to the UK...partially because of invitations and friendships started at Mudcat!
Lots of points have been made about the distances, the types of 'folk clubs', the variable sense of 'identity' in various countries and the 'history' factor of the music. I find that I have learned much from reading about music from those who have had certain aspects of for several hundred years...and I know that stuff that grew largely in the US has made its way abroad.

....so, even though it may well be that more Brits have joined and a few Americans have dropped out, it's not exactly a process we can control easily....(as Yogi Berra said, "If folks are gonna stay away in droves, you can't make 'em!")...but I think the WHOLE is better than it would be without Mudcat, the DT database, and the technology to interact quickly and cheaply with like minded people from all over the world.