Over the past decade I have noticed that I start a great many more books* than I finish. I used to finish most of the books I read -- at least 90%, I'd say. Now, looking at the last 20 books I've checked out of the library (excluding cookbooks), I see that I have finished nine.
(I'm only able to do this because our library page now has a "Reading History" link for everyone's account. I'm not sure how I feel about this. In theory, this data is available only to me. In fact, obviously, if the data exists, it can be made available to anyone. In these days when Moms for Liberty and indeed the entire "conservative" camp, is looking to make certain ways of existing a legal offense, collecting data in this fashion worries me, just a bit.)
If we go back 50 books, for a broader sample, I have finished 24/50. (Again, excluding cookbooks.)
If we go back 100 -- excluding cookbooks and re-reads -- it's 42/100, but some of those are re-reads, so I don't know how to evaluate that number. Let's stick with 24/50. I'm finishing less than half the (new) books I check out of the library.
Is this because the quality of books being published is worse than it was ten years ago?
Maybe.
But there are other possibilities:
(1) I am less exacting about the books I check out than I used to be. I'm pretty sure this is true, since I can remember noticing that when I "took a chance" on a book I wasn't sure I would like, sometimes I really, really liked it, and that gave me a new writer, even a new genre, to read. (I'm looking at Georgette Heyer here.) So it's possible I'm taking more chances on what I check out.
(2) I'm less interested in finishing books I'm not enjoying. This is to say, I've given myself permission not to finish a book if I'm not having a good time. File under life-is-too-short.
(3) I'm reading, or at least sampling, books in the SF/F books I would not have checked out before, because I'm looking for books I might want to use in a review. This would explain an increase in DNF over the past couple years, since I started reviewing seriously for two SF magazines. I'd say maybe five or six books out of the hundred fit that category. On the other hand, I finished a couple of books I would not have, because I was hoping to review them. So that probably washes out.
It could also be that books are in fact getting worse. I don't think you can prove it with my data, is all I'm saying.
*I thought about giving examples of the books I wasn't finishing here, but I think that would be too mean. It may have nothing to do with the quality of the books. It may just be that I'm the wrong reader for whatever the book is. Anyway, if you're an author googling for your book, your book is wonderful! I'm absolutely not talking about your book here!