It doesn't matter!
That is the wonderful aspect of the digital camera. We are no longer constrained in the numbers of images we shoot by economics - only by time, our own patience and, of course, the patience of those tiny little critters which we shoot.
I will often keep as few as one out of fifty or a hundred images. This is not to say that 49 out of 50 images or 99 out of a hundred are bad. I will shoot multiple images with just tiny differences in lighting, composition or exposure. Often there will be multiple images which are pretty equal in quality and then I have to decide which one or two I will keep. Why, jam up my computer by keeping virtual duplicates. Of course there will often be times when just one shot is head and shoulders above the rest. Of course, I keep this shot. However, the others may be very good shots also, just not quite up to the standards of the primo image. They go into the junk pile also.
My mother regarded photographic images with reverence. She would keep anything that came back from the corner drug store where the family got the images processed and printed. It didn't matter how badly out of focus an image was or even if the photographer had inadvertently snapped a picture of the corner of the ceiling by mistake - all of it went into Mom's photo box. I was determined to be more selective and to cull my images resolutely.
Naturally, I also shoot my percentage of out of focus or badly framed junk which are easy to dispose of.
