I'm with Cryptid on that last point, at least to some extent. As for at this point we can't even be certain if what's being seen as "large hairy hominid" even represents a single species, or a spectrum of diverse species created by successive waves of migration, or speciation through isolation or selective factors within a habitat....as relatively closely related forms, hybridization may be ongoing, unless inhibited by their own cultural norms. But I do believe that eventually, or maybe tomorrow, proof/evidence of definite nature will be had. Of course the governmemt may finally choose disclosure of what they know as well..
As for the percentage of sightings that get reported to various record keeping groups, I d personally guess its no more than 5-10% at the very best, and probably well below that. Figure Joe Average may not even be aware of Bigfoot groups prior to a sighting, this their first recourse would be to call the police, or perhaps the forest service, which would usually result in mirthful dismissal, which could well make them all the more reluctant to pursue further efforts to report. Most nigfoot groups on say Facebook that I've seen run rampant with harshly critical elements that offer up more than enough critique, criticism, and questions of personal sobriety to turn anyone's thought away from reporting anything ever again!