Depends on what you consider 'prints' and percentage of what, total snaps or of the "keepers". Of total snaps, most of which are discarded, I'm sure the number is waaaaaay less than 1%. If you're talking about percentage of shots that I like enough to keep, I'd say it depends. In terms of actual prints on individual sheets of paper that I hang somewhere in my house or other people hang somewhere, still probably in the neighborhood of 1% or less. But I've done three photo-books already that commit photograph to actual paper and ink and, if you count those, I'd say it might be as high as 5%. But even if i consider 200-300 shots from that past year that made it onto some form of paper, that still really isn't much. Jeez, I brought about 3000 shots back from Europe last summer and I'd already culled a lot of the garbage each evening. Most of those didn't survive, but I took a LOT of photographs and keep maybe as many as 20% of them on the computer, and, of those, even 5% sounds high. So, I'm the single vote (at this point) for <5%.
-Ray