The statistic comes from a talk at this year's 31C3 In Germany and was delivered by a professor from the University of Portsmouth -- Dr. Gareth Owen.

His personal site: https://ghowen.me/other.html

And a direct link to the video: https://www.youtube.com/watch?v=oZdeRmlj8Gw

I'd imagine he'll publish a full write-up soon but the talk was only a few weeks ago so il not surprised it's not out yet.