I'm trying to find out what proportion of email users can't/don't view images; whether they have chosen to turn them off, or don't click to download them.

Does anyone know of any recent stats on this?

I found a whitepaper from 2009 which seems to suggest a split of 48/52% in favour of those who block images, but I'm sure times have changed since then: http://www.customerinsightgroup.com/marketinglibrary/wp-content/uploads/2009/04/view-from-the-inbox-2009.pdf