>>4078925pareto principle/power rule
80% of the photos that you shoot will be discarded
of the remaining 20%, 80% will be unremarkable
of the remaining 4%, 80% will not be something significant that you ABSOLUTELY MUST SHOW
that leaves 0.8% of the photos that you take being really, really good photos
if you shoot 500 photos per year, that's four photos that are portfolio quality
My experience has been comparable to this, and all of this is totally relative to your skill level. That's 0.8% of photos that are of sufficient quality to put in a CASUAL, FAIRWEATHER AMATEUR PHOTOGRAPHER's portfolio