I own between 1,200 and 1,500 paper books. Yes, I've read all of them. When I got my Kindle, I got rid of my paper TBR pile. I knew I'd never want to read another paper book again. I've since changed my mind about that since some of my faves (Hello, JKR) aren't available as e-books.
Over the last 10 years, I've probably donated about 5,000 paper books, most of which I had already read.