I wonder if Steve Gardham could help me out with this one -

I am currently working on a review of Vaughan Williams in Norfolk: Volume 2. This is a fascinating and very informative CD-Rom recently released on the 'Musical Traditions' label (MTCD255) and covers just about all aspects of this part of this important collection. Volume 2 covers The 1908-11 collection from the Broads & South.
It seems that Vaughan Williams collected 93 folk songs in this part of the county in these years. We know that VW was a stickler for going for what he saw as the genuine article. A quick glance through the very detailed Index suggests that 91 of them can be sourced to Broadside or Chapbook.

Does Steve think that he could work the percentage of the songs that were printed in this way for me?