Up to 100% for me.
I pretty much never re-read. So before I was paying for paperbacks that I'd then have to hassle with donating, giving away etc. since I don't like having books I'll never read again wasting space in my condo.
So I'm happy to pay the same for an e-book. I'm paying for the experience of reading the book, more than to own the book, when it comes to my leisure reading. The experience is the same either way, so I'm fine with the same price.
But I see how others who are more collector types etc., or people who do re-read often, wouldn't want to pay as much for the e-book.