This is a well-bandied statistic on the internet - "80% of technical information is found only in patents". (the corollary being, "therefore you need to search patents" - no argument here) But I'm trying to find some definitive proof for this, the piece of research that everyone is apparently citing, because nobody seems to actually give the citation.
I can find presentations on the EPO website giving this figure as gospel, but with no research citation to support it. Everyone else seems to be quoting the EPO, and even ripping off their slides, which is an interesting take on copyright protection! I can find nothing on the WIPO website, or the European Commission website (other than EPO stuff), but their search engines aren't really letting me look for what I want to look for. So where did this 80% figure come from? And how do we know it's true?
If anyone can point me at original research proving the point, I'd be grateful. It's for a potential article for a general information professional audience (non-patent specialists), so they would expect proper citations if I'm spouting 'facts' at them.