I did quick internet search and only app mentioned by people that is able to achieve such compression rate is KGB Archiver[1]. And according to its wikipedia page it uses PAQ[2].<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;KGB_Archiver" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;KGB_Archiver</a>
[2] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;PAQ6" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;PAQ6</a>