Averages are definitely going to be skewed here -- I suspect that most people on these boards who don't have great ratios here are not going to post.
I'm at 9% at age 32.
I'm not proud of it, but I'm not not proud of it, either. That rate represents a mix of not having had certain advantages and also not having been as smart as I could have been. I've been working since I was 15, and have been financially independent since I was 18; I paid my way through college and grad school on a very small budget without family assistance. I spent about three years after finishing grad school being unfocused and not realizing that maintaining my grad school lifestyle could have significant benefits for me (had small savings and started a 401k once I had access but just wasn't focused), and in 2017 decided that I needed to really start shaping up.
Putting yourself through school's not a joke, and the opportunity cost of grad school is real; I didn't make more than $25k in a year until 2015, and I had to take out loans for my undergrad because my family couldn't help. All the same, that number would be more like 14-20% if I had stayed on my shoestring grad school budget after finishing up instead of the lifestyle inflation I practiced.