It's SNP voting levels from 2012 elections - not a particularly appropriate measure in my opinion!
Edit: The reason why I don't think it's appropriate is that it is a simple "Yes" or "No" and a lot of people who may have traditionally voted Labour or Lib Dem might be voting "Yes" even though the national UK parties have all been pushing the "No" side of the campaign.
Edit: The reason why I don't think it's appropriate is that it is a simple "Yes" or "No" and a lot of people who may have traditionally voted Labour or Lib Dem might be voting "Yes" even though the national UK parties have all been pushing the "No" side of the campaign.