How much of the NES/Famicom library doesn't yet have an identified bootleg? The line between that and repros can be blurry, mind you.
I believe at least one half to 2/3rds there are no bootlegs.
I own about 1/3rd of the Famicom licensed library in bootleg format, and after looking at dozens of pictures of other peoples collections (and also talking with other collectors), it seems that there were a lot of titles that no one has yet to see a bootleg version of.