I'm a bit sceptical about those kind of statistics. My instinct is to think that it is all a lot more complicated and much patchier, and goes in circles.

For example I'd reckon there are a lot more people playing concertinas and such like than there were forty years ago. And there is far more folk music in bars than you'd have found then either. And the technical standard of musicianship among those playing it is far higher.

Swings and roundabouts.