The OP reports:
Pleased that my post has generated some discussion.
It's not important but I'd be interested in any knowledgeable response to my original question. Not an opinionated 'you guys don't understand it...', not a comment on how prog was consumed in its commercial heyday, just something like 'my impression is that it's more popular now than twenty-five years ago, but a bit less than it was five years ago...'.
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