That percentage would be somewhat higher than my 89% which is the percentage of the general corpus (English) that form the earliest extant version.

'sourced to Broadside or Chapbook'. By this do you mean a specific locally produced broadside or Chapbook or just broadside versions in general?

'desk-bound urban outsiders'.(JC) These are Jim's descriptions and no-one else's. Of course the broadside poets came from a wide variety of backgrounds. There was enormous migration from rural to urban, plus at the ends of the wars, soldiers and sailors cast onto the streets. It would have been logical for some of these with a little literacy to have turned their hands to writing ballads, again that's apart from all the material coming in from other commercial sources.
The idea that they were desk-bound is ludicrous.

JC keeps quoting Irish songs at us as if these are relevant to the corpus we are talking about. Let him give us an English example of a song in the corpus that couldn't have been written by an urban writer. (I've already offered to look in detail at Walter's repertoire)