It's a good question but, if 'You Are My Sunshine' is the kind of thing you're looking for, I'd love to know whether there's a difference in how well-known it is between 'ordinary people' in (a) the 60+ age-group, (b) the 40-60s, and (c) the 20-40s.

Plenty of pop festival goers can sing along with every song in the repertoires of the bands onstage, but what's more interesting is how many songs survive through succeeding generations without the continuing stimulus of the artist or band being around to perform them, or TV ads usage, etc.

And lots of people know the chorus of 'Yellow Submarine', but how many could sing a whole verse without a crib sheet?