I dunno what percentage I've read or listened to but it's definitely under 20%. I say this as someone who got his first miniatures at the age of nine (some Squats squats, one had a meltagun and I painted it black and gold) and has been into the hobby ever since, on and off (mostly on, sometimes autistically deep into it) and although I've never really played any of the main games I did used to be a big fan of the lore. Most of the authors are shit though, imo. This is subjective ofc but not an opinion unique to me. I still really like their best stuff even after all this time but you have to sift through mountains of garbage to find it. I tend to go by author, and if it's a new guy I try to find their short stories to form an opinion. Unfortunately though, I've found that many of them can write a very compelling short yet fail miserably when it comes to a novel, which isn't surprising, I imagine novels are a lot more taxing.