As an award-winning data analyst and strategist in my past life, and someone recently featured in Publishers Weekly for my activism, I can tell you you're never going to solve author income through sales channel analysis. It's who holds the microphone and whether we're allowed to talk about it.
The survey found that only 25% of print books and e-books read in the past month were bought new or through a paid subscription, with readers increasingly turning to low- or non-royalty generating channels to access authors’ work.